Absorbent members having skewed density profile

ABSTRACT

Absorbent members and methods of making the same are disclosed. In one embodiment, the absorbent member is a unitary absorbent fibrous web having a density profile through its thickness. In such an embodiment, the density profile of the fibrous web is skewed toward one of the surfaces of the fibrous web. In such embodiments, the maximum density of the web may be located outside of the central 30% zone of thickness of the web.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/094,279 filed on Apr. 26, 2011.

FIELD OF THE INVENTION

The present invention is directed to absorbent members and methods ofmaking the same, and more particularly to absorbent members and methodsof making the same that provide the absorbent members with a controlleddensity profile.

BACKGROUND OF THE INVENTION

Currently, some disposable absorbent articles such as diapers, sanitarynapkins, and pantiliners are provided with a low density airfeltabsorbent core. Airfelt, or comminuted wood pulp, is typically made in aprocess that involves several steps. The first step is one in which pulpfibers are suspended in water and introduced to a moving screen from theheadbox in a wetlaid paper process. The water is removed by acombination of gravity and vacuum before introduction to a dryingprocess to form a relatively high basis weight material that is referredto as “drylap”. Drylap may be in sheet or roll form. Thereafter, thedrylap is shipped to the absorbent article manufacturer. The absorbentarticle manufacturer subjects the drylap to comminution process orshredding to make airfelt or “fluff” via an airlaid process. This istypically done on-line in an absorbent article manufacturing line.

Airfelt has several limitations when used as an absorbent core materialin disposable absorbent articles. Airfelt typically has low integrity,and is subject to bunching and roping when wet. Airfelt typically has alow density and cannot provide as much capillary work potential as ahigher density material. In addition, airfelt has the same densitythroughout the thickness, and is not readily formed into structureshaving a density gradient should it be desired to provide a corestructure with zones having different properties.

Airlaid structures are another type of absorbent material commonly usedin absorbent articles. The air laying process involves the comminutionor shredding of drylap to make airfelt or “fluff”. Binder materials,such as latex binder, may then be added to provide strength andintegrity to the material. Super-absorbent polymers are often added inthe air laying process as well. Airlaid structures can be formed in amanner which does provide a density gradient, as in US 2003/0204178 A1,but this involves more expensive processes and materials. The air layingprocess is often done at an intermediate supplier, resulting in addedcost for shipping the material to the converting operation. Thecombination of more costly materials, processing and shipping result ina significantly more expensive material and a more complex supply chain.

Various different absorbent structures and other structures used inabsorbent articles, and methods of making the same, are disclosed in thepatent literature, including: U.S. Pat. No. 3,017,304, Burgeni; U.S.Pat. No. 4,189,344, Busker; U.S. Pat. No. 4,992,324, Dube; U.S. Pat. No.5,143,679, Weber; U.S. Pat. No. 5,242,435, Murji; U.S. Pat. No.5,518,801, Chappell, et al.; U.S. Pat. No. 5,562,645, Tanzer, et al.;U.S. Pat. No. 5,743,999, Kamps; U.S. Patent Application Publication No.2003/0204178 A1, Febo, et al.; U.S. Patent Application Publication No.2006/0151914, Gerndt; U.S. Patent Application Publication No.2008/0217809 A1, Zhao, et al.; U.S. Patent Application Publication No.2008/0221538 A1, Zhao, et al.; U.S. Patent Application Publication No.2008/0221539 A1, Zhao, et al.; U.S. Patent Application Publication No.2008/0221541 A1, Lavash, et al.; U.S. Patent Application Publication No.2008/0221542 A1, Zhao, et al.; and, U.S. Patent Application PublicationNo. 2010/0318047 A1, Ducker, et al. However, the search for improvedabsorbent structures and methods of making the same has continued.

It is desirable to provide improved absorbent members and methods ofmaking the same. In particular, it is desirable to provide absorbentmembers with improved liquid acquisition, flexibility, tensile strength,and fluid retention. Ideally, it is desirable to produce such improvedabsorbent members at a low cost.

SUMMARY OF THE INVENTION

The present invention is directed to absorbent members and methods ofmaking the same. There are numerous non-limiting embodiments of thesemembers and methods, and more particularly to absorbent members andmethods of making the same that may be used to provide the absorbentmembers with a controlled density profile.

In one non-limiting embodiment, the absorbent structure comprises atleast one unitary absorbent fibrous layer or web comprising at leastsome cellulose fibers. The fibrous layer has a first surface, a secondsurface, a length, a width, a thickness, and a density profile throughits thickness. The density profile may be substantially continuousthrough the thickness of the fibrous layer. The fibrous layer mayfurther comprise different regions throughout the x-y plane with densityprofiles through their thicknesses. The thickness of the fibrous layercan be divided into a range of distances measured through its thicknessfrom 0% at its first surface to 100% of the distance through itsthickness at its second surface. In certain embodiments, the absorbentlayer comprises a location that has a maximum density and a portion orportions with a minimum density. The mean maximum density measurementthrough the thickness of the layer may be at least about 1.2 times themean density of the portion or portions with the minimum density. In onenon-limiting embodiment, the fibrous layer has a density profile that isrelatively centered in which: (a) the maximum density of the layer islocated between about 35% and about 65%, alternatively between about 40%and about 60%, of the distance through the thickness of the layer; and(b) the mean maximum density measurement through the thickness of thelayer is at least 1.2 times the mean density of the layer measured atouter zones of the layer where the outer zones of the layer are: (1)between 5% to 15%; or (2) between 85% and 95% of the thickness of thelayer.

In other embodiments, the density profile of the fibrous layer is skewedtoward one of the surfaces of the fibrous layer. In such embodiments,(a) the maximum density of the layer is located outside of the zone ofthe layer that is between about 35% and about 65%, alternatively betweenabout 40% and about 60%, of the distance through the thickness of thelayer; and (b) the mean maximum density measurement through thethickness of the layer is at least 1.2 times the mean density of the webmeasured at outer zones of the layer that are: (i) between 5% to 15%; or(ii) between 85% and 95% of the thickness of the layer.

Other embodiments are possible. For example, the absorbent membersdescribed above can be further compacted in regions, or over theirentire surface. In other embodiments, the web can have different regionswith different density profiles. In other embodiments, the absorbentmembers can be provided with a three-dimensional topography. In stillother embodiments, the absorbent members can be apertured.

The methods of forming the absorbent members involve subjecting aprecursor web to at least one cycle (or pass) through a mechanicaldeformation process. The precursor material may be in roll or sheet form(e.g., sheet pulp). The precursor material may comprise any suitable wetlaid cellulose-containing material, including but not limited to:drylap, liner board, paper board, post-consumer recycled material,filter paper, and combinations thereof. The methods may involve passingthe precursor web through a pair of counter-rotating rolls. The surfaceof the individual rolls may, depending on the desired type ofdeformation, be: smooth (i.e., an anvil roll) or provided with formingelements comprising protrusions or “male” elements. Typically, themethods involve subjecting the precursor web to multiple cycles (orpasses) through a mechanical deformation process. The mechanicaldeformation process may utilize a “nested” roll arrangement in whichthere are at least four rolls and at least two of the rolls define twoor more nips with the other rolls.

The methods described herein may be used for a variety of purposes. Suchpurposes can range from serving as a pre-processing step prior tofeeding the precursor material into a hammer mill in order to reduce theenergy required to defibrillate the material in the hammer mill, toserving as a unit operation in an absorbent article manufacturing linein order to prepare a completed absorbent member that is ready for usein an absorbent article being made on the line.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description will be more fully understood in viewof the drawings in which:

FIG. 1 is a scanning electron microscope (SEM) image of thecross-section of a web of dry lap.

FIG. 1A is a graph of the micro CT density profile throughout thethickness of a web of dry lap.

FIG. 2 is a photomicrograph of the cross-section of a web of dry lapafter it has been processed according to one embodiment of the presentmethod to form a two-side de-densified absorbent member.

FIG. 3 is a perspective micro CT scan image of an absorbent member ofthe type shown in FIG. 2.

FIG. 4 is a graph of the micro CT density profile of several absorbentmembers such as those shown in FIGS. 2 and 3.

FIG. 5 is a photomicrograph of the cross-section of a web of dry lapafter it has been processed according to another embodiment of thepresent method to form a one-side “de-densified” absorbent member.

FIG. 6 is a graph of the micro CT density profile through the thicknessof four absorbent members similar to the absorbent member shown in FIG.5.

FIG. 7 is a photomicrograph of the cross-section of an absorbent memberthat has a portion thereof, on the left side of the image, which hasbeen re-densified or compacted.

FIG. 8 is a photograph of a web of dry lap after it has been processedaccording to another embodiment of the methods described herein in orderto form a three dimensional absorbent member.

FIG. 9 is a photograph of a web of dry lap after it has been processedaccording to another embodiment of the methods described herein in orderto form an apertured absorbent member.

FIG. 10 is a perspective view photomicrograph of an absorbent memberthat has a portion thereof, in the center of the image, which has beenre-densified or compacted in order to form an absorbent member havingX-Y regions with different densities.

FIG. 11 shows a web of dry lap after it has been processed according toanother embodiment of the methods described herein in order to form anabsorbent member with “regional de-densification”.

FIG. 12 is a schematic side view showing various embodiments of anabsorbent structure comprising a first absorbent member that has adensity profile through its thickness comprising a relatively higherdensity zone disposed in the Z-direction between two relatively lowerdensity outer portions of the layer, and that comprises a secondabsorbent member adjacent to one surface of the first absorbent member.

FIG. 13 is a schematic side view showing various embodiments of anabsorbent structure comprising a first absorbent member that has adensity profile through its thickness comprising a relatively lowerdensity outer portion of the layer disposed in the Z-direction adjacentto a relatively higher density zone, and that comprises a secondabsorbent member adjacent to one surface of the first absorbent member.

FIG. 14 is a cross-sectional side view of two embossing members in aprior art embossing process.

FIG. 15 is a schematic side view of one embodiment of an apparatus formaking an absorbent member, such as a two side de-densified absorbentmember shown in FIG. 2.

FIG. 15A is a schematic side view of another embodiment of an apparatusfor making an absorbent member.

FIG. 15B is a schematic side view of another embodiment of an apparatusfor making an absorbent member.

FIG. 15C is a schematic side view of another embodiment of an apparatusfor making an absorbent member.

FIG. 15D is a schematic side view of another embodiment of an apparatusfor making an absorbent member.

FIG. 16 is an enlarged perspective view of one non-limiting embodimentof the surfaces of two of the rolls in the apparatus.

FIG. 17 is a further enlarged perspective view of the surfaces of therolls shown in FIG. 16.

FIG. 18 is a schematic plan view of an area on a web showing how theteeth on the two rolls could align in the nip.

FIG. 19 is a cross-section of a portion of the intermeshing rolls.

FIG. 20 is a photograph of a web between a portion of the intermeshingrolls.

FIG. 21 is a schematic side view of another embodiment of an apparatusfor making an absorbent member.

FIG. 22 is a schematic side view of one embodiment of an apparatus formaking an absorbent member, such as a one side de-densified absorbentmember shown in FIG. 5.

FIG. 23 is a schematic side view of one non-limiting embodiment of anapparatus for making a re-densified/compacted absorbent member such asthat shown in FIG. 7, or a three-dimensional or apertured absorbentmember such as shown in FIGS. 8 and 9, respectively.

FIG. 24 is a schematic side view of one non-limiting embodiment of anapparatus for making a three-dimensional or apertured absorbent membersuch as shown in FIGS. 8 and 9, respectively.

FIG. 25 is a schematic side view of one non-limiting example of aforming member for the step of forming the precursor web into a threedimensional absorbent member.

FIG. 26 is a perspective view of another example of a forming member forthe step of forming the precursor web into a three dimensional absorbentmember.

FIG. 27 is a schematic side view of one non-limiting example of aforming member for the step of forming the precursor web into anapertured absorbent member.

FIG. 28 shows one non-limiting example of a forming member for the stepof forming the precursor web into an absorbent member wherein a portionof the absorbent member has been re-densified or compacted.

FIG. 29 shows one non-limiting example of a forming member for the stepof forming the precursor web into an absorbent member with regionalde-densification.

FIG. 30 is a schematic top view showing the specimen for the micro CTtest method.

FIG. 31 is a schematic side view of the region of interest (ROI) of aspecimen analyzed by the micro CT test method.

FIG. 32 shows a perspective view of the surface of another embodiment ofa roll that can be used in the methods described herein.

The embodiments of the absorbent structure and methods of making thesame shown in the drawings are illustrative in nature and are notintended to be limiting of the invention defined by the claims.Moreover, the features of the invention will be more fully apparent andunderstood in view of the detailed description.

DETAILED DESCRIPTION

Definitions

The term “absorbent article” includes disposable articles such assanitary napkins, panty liners, tampons, interlabial devices, wounddressings, diapers, adult incontinence articles, wipes, and the like.Still further, the absorbent members produced by the methods andapparatuses disclosed herein can find utility in other webs such asscouring pads, dry-mop pads (such as SWIFFER® pads), and the like. Atleast some of such absorbent articles are intended for the absorption ofbody liquids, such as menses or blood, vaginal discharges, urine, andfeces. Wipes may be used to absorb body liquids, or may be used forother purposes, such as for cleaning surfaces. Various absorbentarticles described above will typically comprise a liquid pervioustopsheet, a liquid impervious backsheet joined to the topsheet, and anabsorbent core between the topsheet and backsheet.

The term “absorbent core”, as used herein, refers to the component ofthe absorbent article that is primarily responsible for storing liquids.As such, the absorbent core typically does not include the topsheet orbacksheet of the absorbent article.

The term “absorbent member”, as used herein, refers to the components ofthe absorbent article that typically provide one or more liquid handlingfunctionality, e.g., liquid acquisition, liquid distribution, liquidtransportation, liquid storage, etc. If the absorbent member comprisesan absorbent core component, the absorbent member can comprise theentire absorbent core or only a portion of the absorbent core.

The term “absorbent structure”, as used herein, refers to an arrangementof more than one absorbent component of an absorbent article.

The terms “compaction” and “re-densification”, as used herein, refer toa process step in which the density of a web is increased.

The term “cross direction” means the path that is perpendicular to themachine direction in the plane of the web.

The term “de-densification”, as used herein, refers to a “densityreduction” in which the density of a web is reduced.

The term “density profile”, as used herein, refers to a change indensity through the thickness of an absorbent member, and isdistinguishable from ordinary variations in the density of absorbentmembers having a substantially uniform density throughout the thickness.The density profile can be in any of the configurations describedherein. Density profiles may be illustrated in photomicrographs, SEM andMicro CT Scan images.

The term “discrete”, as used herein, means distinct or unconnected. Whenthe term “discrete” is used relative to forming elements on a formingmember, it is meant that the distal (or radially outwardmost) ends ofthe forming elements are distinct or unconnected in both the machinedirection and cross-machine direction (even though bases of the formingelements may be formed into the same surface of a roll, for example).For example, the ridges on a ring roll are not considered to bediscrete.

The term “disposable” is used herein to describe absorbent articleswhich are not intended to be laundered or otherwise restored or reusedas an absorbent article (i.e., they are intended to be discarded afteruse and, preferably, to be recycled, composted or otherwise disposed ofin an environmentally compatible manner).

The term “drylap”, as used herein, refers to a dried, wetlaidcellulose-containing fibrous material that may be in roll or sheet form.Drylap is also known as fluff pulp or communition pulp. For someapplications, drylap comprises SBSK (Southern Bleached Softwood Kraft)or NBSK (Northern Bleached Softwood Kraft) pulp produced in relativelyheavy caliper, high basis weight sheet form. The sheet product isrewound into continuous rolls or stacks of sheets for shipment to adisposable article manufacturer. At the manufacturer's plant, the rollsare continuously fed into a device, such as a hammermill, to be reducedas much as reasonably possible to individual fibers thereby creatingcellulose “fluff”. Alternatively, drylap grades of material can bede-densified by the processes described herein. In addition to cellulosefibers, drylap can include fibers of rayon, polyester, cotton,post-consumer recycled material, other fibrous materials, or evenparticulate additives comprising items such as mineral fillers, Kaolinclay, or powdered cellulose. Drylap materials of the type useful in thisinvention include those described in U.S. Pat. Nos. 6,074,524 and6,296,737.

The terms “exterior”, “outer”, and “outside”, as used herein withreference to zones of an absorbent member, refer to those zones that arespaced in the z-direction away from a plane that runs through the centerof the absorbent member.

The term “joined to” encompasses configurations in which an element isdirectly secured to another element by affixing the element directly tothe other element; configurations in which the element is indirectlysecured to the other element by affixing the element to intermediatemember(s) which in turn are affixed to the other element; andconfigurations in which one element is integral with another element,i.e., one element is essentially part of the other element. The term“joined to” encompasses configurations in which an element is secured toanother element at selected locations, as well as configurations inwhich an element is completely secured to another element across theentire surface of one of the elements.

The term “layer” is used herein to refer to an absorbent member whoseprimary dimension is X-Y, i.e., along its length and width. It should beunderstood that the term “layer” is not necessarily limited to singlelayers or sheets of material. Thus the layer can comprise laminates orcombinations of several sheets or webs of the requisite type ofmaterials. Accordingly, the term “layer” includes the terms “layers” and“layered”.

The term “machine direction” means the path that material, such as aweb, follows through a manufacturing process.

The terms “mechanically impacting” or “mechanically deforming”, may beused interchangeably herein, to refer to processes in which a mechanicalforce is exerted upon a material.

The term “Micro-SELF” is a process that is similar in apparatus andmethod to that of the SELF process defined herein. Micro-SELF teeth havedifferent dimensions such that they are more conducive to forming tuftswith openings on the leading and trailing ends. A process usingmicro-SELF to form tufts in a web substrate is disclosed in U.S. Patentapplication Publication No. US 2006/0286343A1.

The term “paper board”, as used herein, refers to the class ofheavyweight paper and other fiberboards thicker than 0.15 millimeter,including boxboard, cardboard, chipboard, containerboard, corrugatedboard, and linerboard.

The term “patterned”, as used herein with reference to the formingmembers, includes forming members having discrete elements thereon, aswell as those having continuous features thereon such as the ridges andgrooves on a ring roll.

The term “post-consumer recycled material” as used herein generallyrefers to material that can originate from post-consumer sources such asdomestic, distribution, retail, industrial, and demolition.“Post-consumer fibers” means fibers obtained from consumer products thathave been discarded for disposal or recovery after having completedtheir intended uses and is intended to be a subset of post consumerrecycled materials. Post-consumer materials may be obtained from thesorting of materials from a consumer or manufacturer waste stream priorto disposal. This definition is intended to include materials which areused to transport product to a consumer, including, for example,corrugated cardboard containers.

The term “region(s)” refer to portions or sections across the X-Y planeof the absorbent member.

The terms “ring roll” or “ring rolling” refer to a process usingdeformation members comprising counter rotating rolls, intermeshingbelts or intermeshing plates containing continuous ridges and grooveswhere intermeshing ridges and grooves of deformation members engage andstretch a web interposed therebetween. For ring rolling, the deformationmembers can be arranged to stretch the web in the cross machinedirection or the machine direction depending on the orientation of theteeth and grooves.

The term “rotary knife aperturing” (RKA) refers to a process andapparatus using intermeshing deformation members similar to that definedherein with respect to SELF or micro-SELF. The RKA process differs fromSELF or micro-SELF in that the relatively flat, elongated teeth of aSELF or micro-SELF deformation member have been modified to be generallypointed at the distal end. Teeth can be sharpened to cut through as wellas deform a web to produce an apertured web, or in some cases, athree-dimensionally apertured web, as disclosed in U.S. PatentApplication Publication Nos. US 2005/0064136A1, US 2006/0087053A1, andUS 2005/021753. RKA teeth can have other shapes and profiles and the RKAprocess can also be used to mechanically deform fibrous webs withoutaperturing the web. In other respects such as tooth height, toothspacing, pitch, depth of engagement, and other processing parameters,RKA and the RKA apparatus can be the same as described herein withrespect to SELF or micro-SELF.

The terms “SELF” or “SELF'ing”, refer to Procter & Gamble technology inwhich SELF stands for Structural Elastic Like Film. While the processwas originally developed for deforming polymer film to have beneficialstructural characteristics, it has been found that the SELF'ing processcan be used to produce beneficial structures in other materials, such asfibrous materials. Processes, apparatus, and patterns produced via SELFare illustrated and described in U.S. Pat. Nos. 5,518,801; 5,691,035;5,723,087; 5,891,544; 5,916,663; 6,027,483; and, 7,527,615 B2.

The term “unitary structure”, as used herein, refers to a structure thateither comprises: a single layer, or comprises fully-integrated multiplelayers that are held together by hydrogen bonding and mechanicalentanglement, and are not formed by assembling multiple layers that areformed separately and joined together with attachment means such asglue. An example of a unitary structure is a structure comprisingdifferent types of fibers (such as eucalyptus fibers that may be laiddown over other cellulose fibers to form the outer layers for softnessin tissue making).

The term “upper” refers to absorbent members, such as layers, that arenearer to the wearer of the absorbent article during use, i.e. towardsthe topsheet of an absorbent article; conversely, the term “lower”refers to absorbent members that are further away from the wearer of theabsorbent article towards the backsheet. The term “laterally”corresponds to direction of the shorter dimension of the article, whichgenerally during use corresponds to a left-to-right orientation of thewearer. “Longitudinally” then refers to the direction perpendicular tothe lateral one, but not corresponding to the thickness direction.

The term “Z-dimension” refers to the dimension orthogonal to the lengthand width of the member, core or article. The Z-dimension usuallycorresponds to the thickness of the member, core or article. As usedherein, the term “X-Y dimension” refers to the plane orthogonal to thethickness of the member, core or article. The X-Y dimension usuallycorresponds to the length and width, respectively, of the member, coreor article.

The term “zone(s)” refer to portions or sections through the Z-directionthickness of the absorbent member.

I. Absorbent Members

The present invention is directed to absorbent members and methods ofmaking the same, and more particularly to absorbent members and methodsof making the same that provide the absorbent members with a controlleddensity profile. The methods described herein allow a number ofproperties of the density profile to be controlled or modulated. Thelocation of the zone of maximum density through the thickness of theabsorbent member may be controlled. The amount of the maximum densitycan be controlled. The thickness of the zones with higher and lowerdensity can be controlled. The ratio of the mean maximum density to themean density of the region(s) with lower density can be controlled. Inaddition, any of these properties can be modified across the lengthand/or width of the absorbent member.

The methods described herein can provide a density profile without thecomplications and expense of producing airlaid webs. The densityprofile, unlike that of airlaid structures formed of multiple layers,may be substantially continuous through the thickness of the fibrousweb. More specifically, airlaid structures formed of multiple layers arebelieved to have a step-like density gradient. The density profile ofthe absorbent members described herein, on the other hand, may besubstantially continuous through the thickness of the fibrous web (suchthat when graphed, the density profile may form a substantiallycontinuous curve that is free of major step-changes and/or breaks). Theabsorbent members described herein may, thus, be non-airlaid. As aresult, the absorbent members may be substantially free, or completelyfree of binder material, such as latex binders sometimes used in makingairlaid materials. The absorbent members described herein may, ifdesired, also be substantially free, or completely free of absorbentgelling material, another common ingredient in airlaid materials. Themethods described herein can provide a density profile without thecomplications and expense of adding water and/or heating the precursormaterial.

The absorbent members are made from a “precursor material” that is inthe form of a web or sheet comprising at least some cellulosic material,which may be a paper grade material. The precursor material may compriseany suitable wetlaid material, including but not limited to: drylap,liner board, paper board, post-consumer recycled material, filter paper,and combinations thereof. In some cases, the absorbent members mayconsist of, or consist essentially of, one of these wetlaid materials.

The precursor material will typically comprise a plurality of individualfibers. A large proportion of cellulose fibers can provide for variousadvantages, such as keeping the cost of the web low. In particularaspects of the invention, the precursor material has a fiber content inwhich at least about 90 wt % of the fibers are cellulose, or fibers havea length of not more than about 0.4 inch (about 1 cm). Alternatively, atleast about 95 wt %, and optionally, at least about 98 wt % of thefibers are cellulose, or fibers have a length of not more than about 0.4inch (about 1 cm). In other desired arrangements, the precursor web canhave a fiber content in which substantially about 100 wt % of the fibersare cellulose, or fibers have a length of not more than about 0.4 inch(about 1 cm).

The fibers comprising the precursor material include cellulosic fiberscommonly known as wood pulp fibers. Applicable wood pulps includechemical pulps, such as Kraft, sulfite, and sulfate pulps, as well asmechanical pulps including, for example, groundwood, thermomechanicalpulp and chemically modified thermomechanical pulp. Chemical pulps,however, may be preferred in certain embodiments since they may impartsuperior properties to the precursor material made therefrom. Pulpsderived from both deciduous trees (hereinafter, also referred to as“hardwood”) and coniferous trees (hereinafter, also referred to as“softwood”) may be utilized. The hardwood and softwood fibers can beblended, or alternatively, can be deposited in layers to provide astratified web. U.S. Pat. Nos. 3,994,771 and 4,300,981, describelayering of hardwood and softwood fibers. Also applicable to the presentinvention are fibers derived from recycled paper, which may contain anyor all of the above categories as well as other non-fibrous materialssuch as fillers and adhesives used to facilitate the precursor webmaking. In addition to the above, fibers and/or filaments made frompolymers, specifically hydroxyl polymers may be used in the presentinvention. Nonlimiting examples of suitable hydroxyl polymers includepolyvinyl alcohol, starch, starch derivatives, chitosan, chitosanderivatives, cellulose derivatives, gums, arabinans, galactans andmixtures thereof.

The fibers comprising the precursor material will normally includefibers derived from wood pulp. Other natural fibers, such as cottonlinters, bagasse, wool fibers, silk fibers, etc., can be utilized andare intended to be within the scope of this invention. Synthetic fibers,such as rayon, polyethylene and polypropylene fibers, may also beutilized in combination with natural cellulosic fibers. One exemplarypolyethylene fiber which may be utilized is PULPEX®, available fromHercules, Inc. (Wilmington, Del.).

The fibers are typically held together by interfiber entanglement andhydrogen bonding. The fibers may have any suitable orientation. Incertain precursor materials, the fibers will be aligned predominately inthe direction of the process in which they were formed (or the “machinedirection”) of the forming process.

FIG. 1 is an SEM image of one embodiment of a precursor materialcomprising dry lap. As shown in FIG. 1, the precursor material is asingle layer structure that is generally relatively dense throughout itsthickness. This precursor material is not suitable for use as acomponent of an absorbent article due to its lack of void volume andhigh stiffness. Table 1 in the Examples section shows the properties oftwo such precursor materials. A graph showing the density of suchprecursor materials with the distance through the thickness T of theprecursor materials shown on the x-axis and the corresponding density ofthe precursor material at those locations on the y-axis are shown inFIG. 1A. Such graphs can be prepared from micro CT scans conducted inaccordance with the Micro CT Scan procedure set out in the Test Methodssection. As shown in FIGS. 1 and 1A, there are some less dense portionsat the surface of the precursor material, but these do not comprise asignificant portion of the overall thickness of the precursor material.The methods described herein reduce the overall (that is, average)density and stiffness of the drylap (or other precursor material) andincrease its void volume in at least some zones thereof so that it issuitable for use as an absorbent member in an absorbent article. Themethods may also increase the average caliper of the precursor material.

The precursor material may have any suitable properties. The burststrength of the precursor material may be as high as 1,500 kPa or more,measured according to TAPPI test method T 403 om-91 for Burst Strength.Generally, precursor materials with lower burst strengths are moreeasily mechanically modified to reduce their density (that is,“de-densified” by a “density reduction” process). This is shown in Table2 in the Examples section provided at the end of this description. Table2 shows the caliper increases are greater in drylap samples having lowerburst strengths. Therefore, it may be desirable for the precursormaterial to have a burst strength less than 1,500, 1,400, 1,300, 1,200,1,100, 1,000, 900, 800, 750, 700, 600, 500, 400, 300, 200, or 100 kPa,or less. The burst strength may also fall within any range between anyof these burst strength numbers.

The precursor material may have any suitable caliper, basis weight, anddensity. Drylap generally has a caliper of at least about 0.04 inch orgreater, e.g., from about 0.04 to about 0.06 inch (about 1-1.5 mm)However, applicants have had drylap specially made having calipers aslow as 0.02 inch (about 0.5 mm) Thus, in some embodiments, the caliperof the precursor material may range from about 0.02 to about 0.06 inch(about 0.5-1.5 mm) Drylap that is commercially available typically has abasis weight of between about 100 and about 200 pounds/1,000 ft²(490-980 gsm). However, applicants have had drylap specially made havinga basis weight as low as 20 pounds/1,000 ft² (98 gsm), or less. Thus, insome embodiments, the basis weight of the precursor material may rangefrom about 20 pounds/1,000 ft² (98 gsm) to about 200 pounds/1,000 ft²(980 gsm). In some embodiments, the precursor web material may have adensity of between about 0.25 g/cc and about 0.6 g/cc, or above,alternatively between about 0.3 g/cc and about 0.6 g/cc. Typically, suchprecursor materials will have a relatively uniform density throughouttheir thickness. For example, the mean maximum density measurementthrough the thickness of the precursor material will typically be lessthan or equal to about 1.1 times the mean density of the portion orportions with the minimum density.

The precursor material may have any suitable moisture content. Drylapusually has a moisture content of less than about 10 percent, e.g.,about 7 percent, although lower and higher moisture contents can beused. Generally, precursor materials with lower moisture contents aremore easily mechanically modified to reduce their density(“de-densified”). For example, it may be desirable for the precursor webmaterial to have a moisture content less than or equal to 10%, 9%, 8%,7%, 6%, 5%, 4%, 3%, 2%, 1%, or any range between any of thesepercentages.

The precursor material may, in certain embodiments, be treated,partially treated (that is, having treated portions and untreatedportions), or untreated. If the precursor material is treated, it may beprovided with any suitable treatment, including but not limited todebonders such as chemical debonders. Examples of suitable treatmentsare described in U.S. Pat. Nos. 6,074,524, 6,296,737, 6,344,109 B1, and6,533,898 B2. Typically, untreated precursor materials will have ahigher burst strength than treated or partially treated precursormaterials. Providing the precursor material with at least some treatmentin the form of a debonder can permit the precursor material to be moreeasily mechanically modified to decrease its density.

The absorbent members formed by the methods described herein may haveany suitable overall properties. The absorbent member may have anaverage flexure-resistance of less than or equal to about 25N, or anylesser flexure resistance value including, but not limited to, less thanor equal to about 10N. The absorbent member may have an average densityrange of between about 0.05-0.5 g/cc. It should be understood that theaverage density ranges of the various possible precursor materials andthe absorbent members described herein may overlap. This is due to thewide variety of possible precursor materials. For a given precursormaterial, the average density of the absorbent member formed herein willbe less than that of the precursor material. The methods describedherein can form absorbent members with any suitable average density,including but not limited to an average density less than, equal to, orgreater than 0.25 g/cc with high flexibility. The methods can also formabsorbent members with any suitable thickness, including but not limitedto less than or equal to 4 mm, or greater than 4 mm.

The location of the portion of the absorbent member with the maximum (orpeak) density may be in the approximate center of the absorbent member(that is, approximately 50% of the distance through the thickness of theabsorbent member). Alternatively, the location of the maximum densitymay vary by up to 30%, or more of the distance through the thickness ofthe absorbent member, such that it may occur anywhere between about 20%up to about 95% of the distance through the thickness of the absorbentmember. The lower end of this range (for example, the 20% point) may beformed on either side of the absorbent member when it is made; however,the lower density portion of the absorbent member will typicallycomprise the upper surface when the absorbent member is incorporatedinto an absorbent article. The absorbent member may have a mean maximumdensity range measured at the peak and at locations +/−5% of thethickness of the absorbent member around the peak of between about0.1-0.65 g/cc. The mean maximum density may, thus, be less than or equalto about 0.25 gm/cc, or greater than about 0.25 gm/cc. The absorbentmember may have a mean minimum density range measured at the locationhaving the minimum density and at locations +/−5% of the thickness ofthe absorbent member around the location having the minimum density ofbetween about 0.02 and one of the following about: 0.15, 0.2, 0.25, 0.3,0.35, 0.4, 0.45, 0.5, and 0.55 g/cc.

The absorbent member may have any suitable ratio of mean maximum densityto mean minimum density (in the lowest density zone outside of themaximum zone, exclusive of the outermost zones that are between 0-4% and96-100% of the distance through the thickness of the absorbent member).These outermost zones are not considered in order to reduce variabilityof the measurements described herein. The term “mean exterior density”,as used herein, refers to the mean or average density measured at outerportions of the absorbent member that are: (1) between 5% and 15%; and(2) between 85% and 95% of the thickness of the layer. When the ratio ofmean maximum density to mean exterior density is specified herein, itrefers to the ratio of the mean maximum density to the outer portionthat has the lowest mean density. The mean maximum density measurementthrough the thickness of the layer may be at least about 1.2 times themean density of the portion or portions with the minimum density. Thisratio may, for example, range from about 1.2 to about 6.5, or more.

The precursor material is modified, as described herein, in order toprovide a unitary absorbent member with a density profile through thez-direction thickness of the absorbent member. The density profile canbe used to provide the absorbent member with at least one relativelyhigher density zone or portion and at least one relatively lower densityzone or portion in the z-direction. The term “relatively”, as used inthis context, means that these zones have a difference in densityrelative to each other. That is, the higher density zone has a higherdensity relative to the lower density zone. There may be two or morezones with different densities. These zones may be designated as first,second, third, etc. zones.

The processes described herein can be tailored to modify the precursormaterial into an absorbent member having many possible structures. Thesestructures include, but are not limited to: (A) an absorbent member witha central higher density zone and outer lower density portions (referredto herein as a “two-side de-densified” absorbent member); (B) anabsorbent member with a higher density portion that is skewed toward onesurface of the absorbent member and a lower density portion adjacentanother side of the absorbent member (referred to herein as a “one-sidede-densified” absorbent member); (C) a re-densified or compacted versionof absorbent members (A) or (B); (D) an absorbent member having adensity profile and a three dimensional topography (3D); (E) anapertured version of absorbent members (A) though (D) described above;(F) absorbent members having X-Y regions with different densities anddensity profiles; and (G) alternative embodiments and combinations ofany of the foregoing types of absorbent members. Each of these types ofabsorbent members and the methods of making the same are described ingreater detail below.

A. to G. Higher Density Central Zone (“Two-Side De-Densified”) AbsorbentMembers

FIGS. 2 and 3 show one non-limiting embodiment of an absorbent member 20with a higher density central zone or a (“two-side de-densified”absorbent member). The absorbent member 20 comprises a unitary absorbentfibrous layer having a first surface 20A, a second surface 20B, a lengthL extending in an X-direction, a width W extending in a Y-direction, anda Z-direction thickness T. As shown in FIG. 2, the thickness T of theabsorbent fibrous layer can be divided into a range of distancesmeasured through its thickness from 0% at its first surface 20A to 100%of the distance through its thickness at its second surface 20B. Theabsorbent fibrous layer has a density profile through its thickness Tcomprising a relatively higher density zone 22 disposed in theZ-direction between two relatively lower density outer zones 24 and 26of the layer. The unitary absorbent fibrous layer may be referred toherein as the “absorbent layer”, the “fibrous layer”, or simply the“layer”.

FIGS. 2 and 3 show that the absorbent member is expanded. By “expanded”,it is meant that the fibers, particularly those in the low densityportion(s), have increased void spacing therebetween in comparison toother parts of the absorbent member (such as in the higher densityportion) and also in comparison to the precursor material shown inFIG. 1. Another way to describe the absorbent member is that theabsorbent member is comprised of cellulose fibers that have surfaces andthere are interfiber hydrogen bonds between cellulose fibers that aresubstantially interrupted by void spaces between the fiber surfaces.Thus, the absorbent member 20 will typically have a low density portionextending in the X-Y plane having a thickness that appears to be“fluffed up” or lofted. The lower density portion will typically besofter than the surface of the precursor web.

The surface 20A of the absorbent member 20 may, or may not, have aplurality of deformations or impact markings therein. The oppositesurface 20B likewise may, or may not, have a similar pattern ofdeformations therein. It should be understood that in the variousdifferent embodiments of the processes described herein, the impactmarkings from the process may be more or less visible (or not visible)depending upon the process used and the configuration of the formingstructure in the apparatus used to form the absorbent member. Thedeformations are present as a result of subjecting the precursormaterial to a mechanical deformation process which imparts localizedbending, strain and shear in order to reduce the density of theprecursor material. The deformations can be in any suitable form,including indentations, protrusions, or combinations thereof. Thedeformations can be arranged in any suitable pattern, including regularpatterns or random patterns. The pattern of the deformations is aproduct of the process and apparatus used to reduce the density of theprecursor material.

The high density portion 22 and the lower density portions 24 and 26 maycomprise any suitable portion of the thickness of the absorbent member20. The high density portion 22 may, for example, comprise between about10%-80%, alternatively between about 10%-50%, alternatively betweenabout 10%-25% of the thickness of the absorbent member 20. The lowerdensity portions 24 and 26 may comprise a significant portion of theoverall thickness of the absorbent member. For example, each of thelower density portions 24 and 26 (or lower density portion, if in otherembodiments, there is only one low density portion) may comprise greaterthan, or greater than or equal to about 5%, 10%, 15%, 20%, 25%, 30%,35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, up to about 80% of theoverall thickness of the absorbent member. The thickness of the lowerdensity portion(s) may also fall within any range between any two of theabove percentages.

In a two-side de-densified structure, the absorbent member 20 may have amaximum density that is at a location between about 35% and about 65%,alternatively between about 40% and about 60% of the distance throughthe thickness T of the absorbent member 20. The absorbent member mayhave a ratio of mean maximum density to mean minimum density of greaterthan or equal to about 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5,3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, or more, or any number or range ofnumbers between these numbers. The ratio may, for example range fromabout 1.2 to about 6.5, or more. Several non-limiting examples of such astructure are provided in Table 3 in the Examples below. A graph frommicro CT scans showing the density profile of these members with thedistance through the thickness T of the absorbent members shown on thex-axis and the corresponding density of the absorbent member at thoselocations on the y-axis are shown in FIG. 4.

Providing the absorbent member with a density profile may provide theabsorbent member with a number of advantages. However, it should beunderstood that the absorbent member need not necessarily provide suchadvantages unless such advantages are specifically included in theappended claims.

The lower density portions 24 and 26 on at least one side of theabsorbent member 20 may provide the absorbent member with void volumefor faster liquid acquisition. It also provides the absorbent member 20with a higher caliper and greater flexibility than that of the precursormaterial.

The higher density portion 22 may provide the absorbent member withcapillary suction to lock away liquids and prevent liquids from comingout of the absorbent article. This is especially useful in reducing thetendency for body fluids to move back towards and rewet the wearer'sbody, (i.e., reduced rewet). The higher capillary suction may alsoenable the use of higher capillary suction topsheets, which may be moreeffective in removing bodily fluids from the wearer's body, leading to acleaner body.

The higher density portion 22 may also provide the absorbent member withimproved integrity relative to prior types of absorbent core materials,such as airfelt. Although the lower density portion will have lessintegrity in comparison to the higher density portion, it will also havemore integrity than airfelt due to the selective breakage andpreservation of hydrogen bonds. Improved integrity is characterized byimproved tensile strength, which makes the absorbent material easier toprocess and handle during the manufacture of absorbent articles.Improved integrity may also reduce bunching, roping, and break-up of theabsorbent material during wear of the absorbent article. In absorbentarticles, such as sanitary napkins and pantiliners, this may lead toreduced staining visible on the body-facing side of the absorbentarticle.

The density profile can be provided in a unitary structure whicheliminates the need to provide separate layers having differentproperties and bonding such layers together. This can eliminate abonding step during processing, and eliminate the need for adhesives orother materials to hold separate layers together (which adhesives mayinterfere with the transportation of liquids between layers).

Absorbent members having a two-side de-densified density profile providethe greatest caliper or thickness in the fewest number of passes througha mechanical deformation process. Caliper or thickness may be ofinterest for those women who prefer thick sanitary napkins.

B. Skewed Density Profile or “One-Side De-Densified” Absorbent Members

FIG. 5 shows a web of dry lap after it has been processed according toanother embodiment of the methods described herein in order to form askewed or “one-side de-densified” absorbent member 20. As shown in FIG.5, the precursor material is formed into an absorbent member 20 thatcomprises a unitary absorbent fibrous layer having a higher density zone22 adjacent one side 20B of the absorbent layer and a lower density zone24 adjacent another side 20A of the absorbent layer. The higher andlower density zones may comprise a significant portion of the overallthickness of the absorbent member. FIG. 6 is a graph of the micro CTdensity profile through the thickness of four absorbent members such asthat shown in FIG. 5.

In such a structure, the absorbent member 20 may have a maximum densitythat is at a location greater than or equal to about 60%, 65%, 70%, 75%,80%, 90%, or 95% of the distance through the thickness T of theabsorbent member, measured from either side of the absorbent member. Incertain embodiments, the skewed density profiled absorbent member 20 mayhave a maximum density that is located outside of the zone thatrepresents the central 20% (distances between 40-60% through thethickness), 25% (distances between 38-63% through the thickness), 30%(distances between 35-65% through the thickness), up to the central 50%(distances between 25-75% through the thickness), or 60% (distancesbetween 20-80% through the thickness) of the thickness of the absorbentlayer. The absorbent member may have a ratio of mean maximum density tomean minimum density of greater than or equal to about 1.2 to about 6.5,or more. The ratio may, for example, range from about 1.2, 1.3, 1.4,1.5, or every additional tenth up to about 6.5, or more. Severalnon-limiting examples of such a structure are provided in Table 4 in theExamples section below.

When the skewed density absorbent member 20 is placed into an absorbentarticle comprising a liquid pervious body-facing side, a liquidimpervious side, the relatively lower density outer portion 24 of theabsorbent member should face the body-facing side of the absorbentarticle.

Absorbent members having a skewed density profile may be useful in thatfor a given caliper, more low density material can be located on thebody-facing side of the absorbent member, which is beneficial for fluidacquisition. Positioning the high density portion on bottom pulls fluidfurther away from body.

C. Re-Densified/Compacted Absorbent Members

FIG. 7 shows a web of dry lap after it has been processed according toanother embodiment of the methods described herein in order to form are-densified or compacted absorbent member 20. In this process, theprecursor material is de-densified such as described in sections IA or Babove, and at least a region of the surface area of the material is thencompacted. As shown in FIG. 7, the absorbent member 20 has a region 30thereof, on the left side of the image, which has been re-densified orcompacted. The region 32 of the absorbent member 20 on the right side ofFIG. 7 has not been compacted and remains de-densified with a higherdensity central zone 22 and two lower density outer zones 24 and 26. Inother embodiments, the entire absorbent member 20 may be re-densified orcompacted.

The structure of a re-densified or compacted absorbent member 20 may besimilar to the two-side de-densified absorbent member, or to theone-side de-densified absorbent member, depending upon which type ofabsorbent member was formed prior to compacting the same. In the case ofthe re-densified or compacted absorbent member, however, the averagedensity of the compacted region(s) of the absorbent member will behigher (and the caliper is lower) than the absorbent member that wasformed prior to compacting the same. The compacted region(s) of theabsorbent member 20 may have a density of between about 0.1 g/cc andabout 0.55 g/cc, while maintaining a density profile therein.

In a re-densified or compacted absorbent member, the majority of theimprovement in flexibility of the de-densified absorbent member is oftenretained. Table 5 in the Examples section shows the difference incaliper and flexibility of a compacted two-side de-densified structurerelative to an uncompacted two-side de-densified structure. Example 15is re-densified or compacted over its entire surface area. Theproperties of the different regions of embodiments in which only regionsof the absorbent member 20 are compacted (as opposed to the entireabsorbent member 20 being compacted) are described in greater detailherein in the section I F.

Absorbent members having a re-densified or compacted density profile canbe useful in that thinness may provide discretion, which is importantfor some consumers. A less preferred alternative approach to there-densification/compaction process described herein would be to attemptto form a thinner absorbent member by mechanically working the precursormaterial less, such as by fewer passes through a mechanical deformationprocess. This will result in less de-densification and less caliperbuild. However, such an absorbent member will remain relatively stiffbecause many of the hydrogen bonds in the precursor material will stillbe present. The compaction approach allows much greater flexibility tobe achieved to form thin absorbent members versus the alternativeapproach of subjecting the precursor material to fewer passes through amechanical deformation process. Table 6 shows an example where ade-densified and compacted absorbent member (Example 17) is thinner andmore flexible than an absorbent member (Example 16) processed with fewerpasses.

D. Three Dimensional Absorbent Members

FIG. 8 shows a web of dry lap after it has been processed according toanother embodiment of the methods described herein in order to form athree dimensional absorbent member 20. In this process, the precursormaterial can be subjected to a process for forming a three dimensionalstructure into the same before and/or after it is de-densified asdescribed in sections IA or B above.

The micro-structure of a three dimensional absorbent member 20 may besimilar to the two-side de-densified absorbent member, or to theone-side de-densified absorbent member, depending upon which type ofabsorbent member was formed prior to or after subjecting the same to astep of forming a three dimensional topography thereon. In thisembodiment, the absorbent member 20 has a density profile and furthercomprises a three dimensional surface topography. More specifically, atleast one of the first surface and second surface comprises protrusions34 and/or depressions. The depressions in one surface of the absorbentmember 20 will typically correspond to protrusions 34 in the othersurface. At least some of the protrusions 34 may have a density profilethrough their thickness wherein the mean maximum density is betweenabout 1.2 and about 6.5, or more, times the mean density of thoseportion(s) through the thickness of the protrusions with the minimumdensity. If the precursor material comprises multiple layers, theprotrusions may be formed in such multiple layers.

The three dimensional absorbent member 20 can have any suitable numberof protrusions 34 and/or depressions therein, from one protrusion 34 ordepression to a plurality of protrusions 34 and/or depressions. Theprotrusions 34 and/or depressions can cover any desired portion of thearea of the absorbent member. In some embodiments, the protrusions 34and/or depressions may be located in a region comprising only a portionof the area of the absorbent member. In other embodiments, theprotrusions 34 and/or depressions may be distributed acrosssubstantially the entire absorbent member.

Absorbent members having a density profile and a three dimensionalstructure may be useful in that the protrusions provide an increase inoverall caliper (which may be important for consumers who prefer thickabsorbent articles).

E. Apertured Absorbent Members

FIG. 9 shows a web of dry lap after it has been processed according toanother embodiment of the methods described herein in order to form anapertured absorbent member 20. In this process, the precursor materialis apertured before and/or after it is de-densified as described insections IA or B above.

The structure of the apertured absorbent member 20 may be similar to thetwo-side de-densified absorbent member, or to the one-side de-densifiedabsorbent member, depending upon which type of absorbent member wasformed prior to aperturing the same, or the type of absorbent memberthat was formed after aperturing the same. In this embodiment, there isat least one aperture 36 extending between said first and secondsurfaces of the absorbent member 20. If the precursor material comprisesmultiple layers, the apertures may extend through such multiple layers.The apertures 36 may be of any suitable shape and size. Suitable shapesinclude, but are not limited to circular, oval, rectangular, etc. Thesize of the apertures 36 can, in some embodiments, range from about 0.25mm² to about 20 mm² in area. The apertured absorbent member may comprisean area 38 at least partially surrounding at least one aperture 36 thatis compacted.

The apertured absorbent member can have any suitable number of apertures36 therein, from one aperture to a plurality of apertures. The apertures36 can cover any desired portion of the area of the absorbent member. Insome embodiments, the apertures 36 may be located in a region comprisingonly a portion of the area of the absorbent member. In otherembodiments, the apertures 36 may be distributed across substantiallythe entire absorbent member.

F. Absorbent Members Having X-Y Regions With Different Densities

There are numerous possible embodiments of absorbent members having X-Yregions with different densities and/or different density profiles. Insome embodiments, the entire absorbent member may have a densityprofile, and the absorbent member may have different regions in the X-Yplane with different densities and/or different density profiles. Inother embodiments, at least a portion of the absorbent member may bede-densified, and a portion is not de-densified. In these latterembodiments, the portion of the absorbent member that is notde-densified may have a density similar to that of the precursormaterial. These latter embodiments will be referred to herein asabsorbent members with “regional de-densification”.

1. Entire Absorbent Member Has Density Profile.

FIG. 10 shows a web of dry lap after it has been processed according toanother embodiment of the methods described herein in order to form anabsorbent member 20 having X-Y regions 40 and 42 with differentdensities and/or density profiles. In one embodiment of such a process,the precursor material is de-densified as described in sections IA or Babove, and is then compacted in at least one region 42.

The structure of the regions of the absorbent member 20 with a densityprofile may be similar to the two-side de-densified absorbent member, orto the one-side de-densified absorbent member, depending upon whichprocess or combination of processes was used to mechanically deform eachregion. The regions can have the same or different types of densityprofiles. For example, in the case where the types of density profilesare different, a first region can have a one-side de-densified profile,while a second region can have a two-side de-densified profile. In suchembodiments, the length and width of the absorbent member define anarea, and the absorbent member comprises at least two regions extendingin the X and Y directions, which comprise: a) a first region comprisinga portion of the area of the absorbent member, and b) a second regioncomprising another portion of the area of the absorbent member. Thefirst region 40 can be said to have a first average density, a firstminimum density and a first maximum density. The second region 42 has asecond average density, a second minimum density and a second maximumdensity. In such embodiments, the second average density of the secondregion 42 is at least about 0.05 g/cc greater than the first averagedensity of the first region.

The first and second regions can be of any suitable size and shape,provided that they are large enough to take a sample/specimen from thesame for the purpose of the Micro CT test method described herein.Therefore, the first and second regions should each cover a region thatis greater than or equal to a square having dimensions of 7.2 mm×7.2 mm(an area greater than or equal to about 52 mm²). The shape of the firstand second regions may be selected from the group including square,rectangular, circular, strips (which may be linear, curvilinear, orcombinations thereof), irregular, combinations, and multiple regions.The size and/or shape of the first region 40 can be the same, ordifferent from that of the second region 42.

The first and second regions 40 and 42 can cover any suitable portion ofthe area of the absorbent member 20 from 1%-99%, provided that the totalof the areas of the two regions does not exceed 100% of the area of theabsorbent member.

Numerous variations of such an embodiment are possible. For example, insome embodiments, the mean maximum densities of the first and secondregions 40 and 42 may be substantially the same. As used herein, withreference to the differences in densities, the phrase “substantially thesame” means that there is less than 0.05 g/cc difference between thedensities. In other embodiments, the second region 42 may have a greatermean maximum density than the first region 40. In some embodiments, thesecond region 42 may have a lower ratio of mean maximum density to meanminimum density than the first the region. In some embodiments, thefirst and second regions 40 and 42 have substantially the sameflexibility. As used herein, with reference to the differences inflexibility, the phrase “substantially the same” means that there isless than 2 N difference in flexibility (that is, flexure resistanceforce). In other embodiments, the second region 42 may have a higherflexure resistance force than the first region 40. In these or otherembodiments, the absorbent member 20 may comprise one or more additionalregions having different average densities relative to the first andsecond regions 40 and 42. These may comprise a third, fourth, fifth,etc. region.

2. Absorbent Members With “Regional De-densification”.

FIG. 11 shows a web of dry lap after it has been processed according toanother embodiment of the methods described herein in order to form anabsorbent member 20 with “regional de-densification”.

In embodiments of absorbent members with “regional de-densification”,the portion 46 of the absorbent member 20 that is not de-densified mayhave a density similar to that of the precursor material 10. Thus, insuch embodiments, the absorbent member 20 comprises at least two regionsextending in the X and Y directions. These regions comprise: a) a firstregion having a density profile through its thickness that comprises aportion of the area of the absorbent member, and b) a second regioncomprising another portion of the area of the absorbent member. Thefirst region 44 has a maximum density, wherein the mean maximum densitymeasurement through the thickness of the absorbent member 20 is at leastabout 1.2 up to about 6.5, or more, times its mean minimum density. Thesecond region 46 of the absorbent member has a mean maximum densitymeasurement through the thickness is less than 1.2 times its meanminimum density, and may have a density similar to that of the precursormaterial.

G. Alternative Embodiments and Combinations

Numerous non-limiting examples of alternative embodiments of theabsorbent members described herein are possible. The embodiments of theabsorbent members can be formed into numerous different types orcombinations of absorbent structures. For example, as shown in FIG. 12,in one embodiment, an absorbent structure 50 can be made that comprisesa second absorbent member 50B adjacent to one surface of a firstabsorbent member 50A, in which the first absorbent member 50A comprisesan absorbent layer that has a density profile through its thicknesscomprising a relatively higher density zone (labeled “High” or “H”)disposed in the Z-direction between two relatively lower density outerportions (labeled “Low” or “Lo”) of the layer. As shown in FIG. 13, inanother embodiment, an absorbent structure 50 can be made that comprisesa second absorbent member 50B adjacent to one surface of a firstabsorbent member 50A, in which the first absorbent member 50A comprisesan absorbent layer that has a density profile through its thicknesscomprising a relatively higher density zone disposed in the Z-directionadjacent to a relatively lower density outer portion of the layer.Numerous other absorbent structures are possible. Several possiblevariations of the arrangements of such higher density, H, and lowerdensity, Lo, zones are shown in FIGS. 12 and 13. These structures mayalso comprise regions of apertures, protrusions, depressions or regionswith different average densities that can extend through one or more ofthe absorbent members 50A and 50B.

II. Methods for Making the Absorbent Members

The methods of forming the absorbent members involve subjecting theprecursor web to at least one cycle or pass through a mechanicaldeformation process.

The mechanical deformation process can be carried out on any suitableapparatus that may comprise any suitable type(s) of forming structures.Suitable types of forming structures include, but are not limited to: apair of rolls that define a nip therebetween; pairs of plates; belts,etc. Using an apparatus with rolls can be beneficial in the case ofcontinuous processes, particularly those in which the speed of theprocess is of interest. Although the apparatuses will be describedherein for convenience primarily in terms of rolls, it should beunderstood that the description will be applicable to forming structuresthat have any other configurations.

The rolls used in the apparatuses and methods described herein aretypically generally cylindrical. The term “generally cylindrical”, asused herein, encompasses rolls that are not only perfectly cylindrical,but also cylindrical rolls that may have elements on their surface. Theterm “generally cylindrical” also includes rolls that may have astep-down in diameter, such as on the surface of the roll near the endsof the roll, and rolls that are crowned. The rolls are also typicallysubstantially non-deformable. The term “substantially non-deformable”,as used herein, refers to rolls having surfaces (and any elementsthereon) that typically do not deform or compress when used in carryingout the processes described herein. The rolls can be made from anysuitable materials including, but not limited to steel or aluminum. Thesteel may be made of corrosion resistant and wear resistant steel, suchas stainless steel.

The components of the forming structure (for instance, the rolls of apair of rolls) such as those shown in FIG. 15, may have any suitabletype of surface. The surface of the individual rolls may, depending onthe desired type of mechanical deformation, be: substantially smooth(i.e., an anvil roll) or provided with forming elements comprisingprotrusions or “male” elements. For rolls comprising ridges and grooves,the ridges are considered to be male forming elements. Male elements maybe discrete (such as SELF teeth, RKA teeth, or pins) or continuous (suchas the ridges on a ring roll). In some embodiments, the components ofthe forming structure may be substantially free of, or completely freeof combinations of discrete male 60 and mating discrete female 62elements such as those shown in FIG. 14 that would be used forembossing. The surfaces with the forming elements may have any suitableconfiguration. Suitable configurations for the forming elements include,but are not limited to: ring rolls; SELF rolls; Micro-SELF rolls; RKArolls and pin rolls.

The forming elements on the SELF rolls can be oriented in either themachine direction (MD) or the cross-machine direction (CD). In certainembodiments, the SELF rolls comprise a plurality of alternatingcircumferential ridges and grooves around the circumference of the roll.The ridges have spaced apart channels formed therein that are orientedparallel to the axis A of the roll. The channels form breaks in theridges that create forming elements or teeth on the SELF roll. In suchembodiments, the teeth have their longer dimension oriented in themachine direction (MD). These roll configurations will be referred toherein as a standard “CD SELF” roll since the teeth are not staggered,and in the usual SELF process, the material being fed into a nip formedby such a roll would be stretched in the cross-machine direction (or“CD”).

In other embodiments, which are described in the SELF patents that areincorporated by reference herein, the SELF roll can comprise a machinedirection, or “MD SELF” roll. Such a roll will have alternating ridgesand grooves that are oriented parallel to the axis A of the roll. Theridges in such a roll have spaced apart channels formed therein that areoriented around the circumference of the roll. The channels form breaksin the ridges to form forming elements or teeth on the MD SELF roll. Inthe case of MD SELF rolls, the teeth have their longer dimensionoriented in the cross-machine direction (CD).

FIG. 32 shows a portion of the surface of a roll having male elements ofanother configuration that can be used in the method. The roll shown inFIG. 32 is referred to herein as a “pin” roll. Unlike the previous toothgeometries described, the teeth of a pin roll are not faceted, meaningthey do not comprise flat faces. The pin tooth can have variouscross-sectional shapes, such as round or oval. The tip of the tooth cancome to a sharp point, be rounded or be truncated so it has a flatsurface. The tooth can also be bent at an angle. The side wall can taperfrom the base to tip at a constant angle, or the side wall can changeangles. For example, the top of the tooth can have a cone-like shapewith a 30 degree angle between the axis of the tooth and the side wall,and the base of the tooth can have a cylindrical shape with a verticalside wall that runs parallel to the axis of the tooth.

To form an absorbent structure which has a higher density portion on oneside, at least one of the components of the forming structure (such asone of the rolls) may have a surface that is: smooth (such as a smoothanvil roll), substantially smooth, or relatively smooth. The phrase“relatively smooth surface”, as used herein, means that the surface ofthe forming structure is not necessarily smooth, but is smoother thanthe surface of the other component of the forming structure. Thus, thephrase “relatively smooth surface” can, for example, include a ringrolling roll that is not smooth, but is “relatively” smoother than aSELF roll used as the other component of the forming structure. Itshould be understood that the phrase “relatively smooth surface” mayinclude smooth and substantially smooth surfaces as well. The smoothnessof the surface refers to the surface area of the forming elements thatis capable of contacting a web. Thus, the larger the total area of theforming elements that is capable of contacting a web, the smoother thesurface will be. To form an absorbent member which has a lower densityportion on both sides, and a higher density region in between, both ofthe components of the forming structure (such as both of the rolls)should have forming elements on their surfaces. If it is desired to skewthe density profile of the absorbent member, at least one of thecomponents of the forming structure (such as one of the rolls) shouldhave a relatively smooth surface. If it is desired to compact theabsorbent member, the forming structures may comprise relatively smoothrolls as compared with those used to de-densify the web.

The rolls are non-contacting, and axially-driven. In cases where therolls in a pair are patterned, the rolls may be meshing, non-meshing, orat least partially intermeshing. The term “meshing”, as used herein,refers to arrangements when the forming elements on one of thecomponents of the forming structure (e.g., roll) extend toward thesurface of the other forming structure and the forming elements haveportions that extend between and below an imaginary plane drawn thoughthe tips of the forming elements on the surface of the other formingstructure. The term “non-meshing”, as used herein, refers toarrangements when the forming elements on one of the components of theforming structure (e.g., roll) extend toward the surface of the otherforming structure, but do not have portions that extend below animaginary plane drawn though the tips of the forming elements on thesurface of the other forming structure. The term “partiallyintermeshing”, as used herein, refers to arrangements when the formingelements on one of the components of the forming structure (e.g., roll)extend toward the surface of the other forming structure and some of theforming elements on the surface of the first roll have portions thatextend between and below an imaginary plane drawn though the tips of theforming elements on the surface of the other forming structure, and someof the elements on the surface of the first roll do not extend below animaginary plane drawn though the tips of the forming elements on thesurface of the other forming structure.

The rolls in the pair of rolls will typically both rotate in oppositedirections (that is, the rolls are counter-rotating). The rolls mayrotate at substantially the same speed, or at different speeds. Thephrase “substantially the same speed”, as used herein, means that thereis less than 0.3% difference in the speed. The speed of the rolls ismeasured in terms of surface or peripheral speed. The rolls may rotateat different surface speeds by rotating the rolls at different axialspeeds, or by using rolls that have different diameters that rotate atthe same axial speeds. The rolls may rotate at substantially the samespeed as the speed at which the web is fed through the nip between therolls; or, they may rotate at a greater or lesser speed than the speedat which the web is fed through the nip between the rolls. The fasterroll may have a surface speed that is anywhere from 1.02 up to about 3times faster than the slower roll. Suitable ranges for the surface speedratio include between about 1.05 and about 2.0, depending on thegeometry of the male elements. The greater the surface speeddifferential or ratio between the rolls, the greater thede-densification of the material.

The precursor web can be fed through the mechanical deformation processin any suitable orientation if the precursor web is in the form ofsheets. If the precursor material is in the form of sheets, theindividual sheets can be joined with their ends in an overlappingconfiguration by passing the sheets through a nip of an RKA or SELFingprocess. Typically, it will be fed into the mechanical deformationprocess in the machine direction if it is in roll form.

The precursor web can be fed through any suitable number of mechanicaldeformation processes. The number of mechanical deformation nips towhich the precursor web is subjected can range from one to between 2 and100, or more, nips.

A. Method for Making Two-Side De-Densified Absorbent Members

FIG. 15 shows one embodiment of an apparatus for making a two sidede-densified absorbent member such as that shown in FIG. 2. Theapparatus shown in FIG. 15 has two pairs of rolls 64 and 66 and may bereferred to as a paired roll apparatus. Each pair of rolls comprises tworolls, 64A and 64B, and 66A and 66B, respectively, that forms a singlenip N therebetween.

In the embodiment shown in FIG. 15, four rolls are shown; however, theapparatus can comprise any suitable number of rolls. The apparatus can,for example, have up to fifty, or more pairs of rolls. Multiple rollsare useful when it is desirable to run the precursor web 10 throughmultiple nips. In order to make the absorbent member 20 shown in FIG. 2,it may be desirable to run the precursor web 10 through as many asthirty or more nips. In order to run the precursor web 10 through thirtynips, if the rolls are arranged in a paired configuration, there wouldhave to be thirty pairs of rolls. However, such roll arrangements areless than optimal since so many rolls are required, and the large numberof rolls will occupy an excessive amount of space on a manufacturingfloor. Therefore, applicants have developed improved configurations forarrangement of the rolls. The rolls can, depending on the embodiment, bearranged in any suitable configuration when viewed from the side,including: paired (FIG. 15); planetary configurations (FIG. 15A) with acentral roll 68 and satellite rolls 70, 72, and 74; nestedconfigurations (FIG. 15B); in the configuration of a closed loop (FIG.15C); in configurations where the rolls are shared by two or more otherrolls (which may be referred to as a “shared bank” (FIG. 15D); andcombinations of such configurations (hybrid) (FIG. 21). These rollconfigurations are described in greater detail in U.S. patentapplication Ser. No. 13/094,206 filed on the same date as the presentapplication, the disclosures of which are hereby incorporated byreference herein.

The apparatus shown in FIG. 15B will be referred to as a “nested roll”arrangement. In the nested roll apparatus, the rolls are arranged in anoffset configuration when viewed from their sides (that is, their ends)in which one roll, such as rolls 78, 82, and 84, is positioned in a gapbetween two adjacent rolls so that at least two of the rolls define twoor more nips N thereon with other rolls. Typically, in a nested rollarrangement, there will be at least four generally cylindrical rolls.More specifically, in a nested configuration, the rolls each have anaxis, A, and the rolls are arranged so that if the rolls are viewed fromone of their circular sides, and lines, such as B and C, are drawnthrough the axes A of at least two different pairs of said rolls (whichpairs may have at least one roll in common), will be non-linear. Asshown in FIG. 15B, at least some of the lines B and C drawn through theaxes of adjacent pairs of rolls form an angle therebetween.

The nested roll arrangement may provide several advantages. A nestedroll arrangement may provide more nips per total number of rolls thannon-nested roll arrangements. This results in the need for substantiallyless tooling (machining of rolls) than in the paired roll apparatus. Thenested roll arrangement maintains control of the web for registeringdeformations in the web since all portions of the web remain in contactwith at least one of the rolls from the point where the web enters thefirst nip to the location where the web exits the last nip. The nestedroll arrangement also has a smaller footprint on a manufacturing floor.The entire nested roll arrangement shown in FIG. 15B could also berotated 90° so that the rolls are stacked vertically, and the apparatuswould occupy even less space on a manufacturing floor.

FIG. 16 is a close up of one non-limiting embodiment of the surfaces oftwo of the rolls 90 and 92 in the apparatus. The rolls 90 and 92 arecarried on respective rotatable shafts (not shown) having their axes ofrotation disposed in a parallel relationship. In this embodiment, eachof the rolls 90 and 92 comprises a variation of one of the Procter &Gamble Company's SELF technology rolls. In this embodiment, the formingelements (or teeth) 100 on the SELF rolls have their longer dimensionoriented in the machine direction (MD).

As shown in FIG. 16, the surfaces of the rolls each have a plurality ofspaced apart teeth 100. The teeth 100 are arranged in a staggeredpattern, which is shown in greater detail in FIG. 17. More specifically,the teeth 100 are arranged in a plurality ofcircumferentially-extending, axially-spaced rows, such as 102A and 102B,around the roll. But for the spacing TD between the teeth in each row,the teeth in each roll would form a plurality ofcircumferentially-extending, axially-spaced alternating ridges andgrooved regions. The tooth length TL and machine direction (MD) spacingTD can be defined such that the teeth in adjacent rows 102A and 102Beither overlap or do not appear to overlap when the rolls are viewedfrom one of their ends. In the embodiment shown, the teeth 100 inadjacent rows are circumferentially offset by a distance of 0.5× (where“x” is equal to the tooth length plus the MD spacing TD between teeth ina given row). In other words, the leading edges LE of adjacent teeth inadjacent rows will be offset in the MD by 0.5×. The rolls 90 and 92 arealigned so that the rows of teeth in one roll align with the groovedregions between the teeth in the other roll. The staggered tooth patternallows the precursor web 10 to be mechanically impacted relativelyuniformly while avoiding the need to time or phase the rolls in themachine direction. The rolls shown in FIG. 16 can be made in anysuitable manner, such as by first cutting the ridges and grooves intothe roll, then helically cutting the teeth 100 into the surface of therolls with each cut being continuous. If desired, the tooth profile (inparticular, the leading and trailing edges) can be modified by using aplunge cut.

The roll configuration shown in FIGS. 16 and 17 will be referred toherein as a “staggered CD SELF” roll since in the usual SELF process,the material being fed into the nip N between such rolls would bestretched in the cross-machine direction (or “CD”). The advantage ofusing CD SELF rolls in the methods described herein is that registrationof multiple rolls to provide multiple hits (impacts within nips) is mucheasier in that it is only necessary to register the toothed regions(that is, to align the toothed regions with the grooved regions on theopposing roll) in the cross-machine direction, and it is not necessaryto phase or register the toothed regions in the MD). FIG. 18 is aschematic plan view of an area on a web showing an example of how theteeth on the two rolls could align in the nip. FIG. 18 shows the areas100A impacted on a web by teeth on roll 90 and areas 100B impacted bythe teeth on roll 92.

FIG. 19 shows in cross section a portion of the intermeshing rolls 90and 92 including teeth 100 which appear as ridges 106 and grooves 108between the teeth 100. The teeth can have a triangular or invertedV-shape when viewed in cross-section. The vertices of teeth areoutermost with respect to the surface of the rolls. As shown, teeth 100that have a tooth height TH, a tooth length TL (FIG. 17), and atooth-to-tooth spacing (or ridge-to-ridge spacing) referred to as thepitch P. The tooth length TL in such embodiments is a circumferentialmeasurement. The outermost tips of the teeth have sides that arepreferably rounded to avoid cuts or tears in the precursor material. Theleading and trailing edges LE and TE (FIG. 17), respectively, of theteeth 100 are preferably square or a shape that creates a relativelysharp edge to maximize de-densification of the web in the process. Asshown, the ridges 106 of one roll extend partially into the grooves 108of the opposed roll to define a “depth of engagement” (DOE) E, which isa measure of the level of intermeshing of rolls 90 and 92. The depth ofengagement can be zero, positive for meshing rolls, or negative fornon-meshing rolls. The depth of engagement E, tooth height TH, toothlength TL, tooth spacing TD and pitch P can be varied as desireddepending on the properties of precursor web 10 and the desiredcharacteristics of the absorbent member 20. For example, in general, toobtain the greatest amount of de-densification in the fewest number ofhits, while preserving a portion of the integrity of the web, it ispreferred to have a short tooth length TL and a small tip radius TR tomaximize the amount of bending around the tooth and minimize the amountof compression on the material. Thus, it may be desirable for the toothtip radius TR to be less than 0.020 inch (about 0.5 mm). However, thismust be balanced with the need to have a tooth that will not easilybreak when the force from the deformation is applied. The tooth spacingTD between the teeth should be large enough to enable the material tobend around the leading and trailing edges, LE and TE, respectively, ofthe teeth. If the TD is too small, the material will bridge the gapbetween the teeth and the amount of de-densification will be lower. Theoptimum pitch of the teeth 100 depends on the thickness of the precursormaterial 10, and is typically around two times the thickness of the web10. If the pitch P is too small, the material 10 will remain fairlydense after multiple passes. If the pitch P is too high, the CD spacingbetween the teeth 100 after the rolls are mated together will be greaterthan the thickness of the web 10 and the teeth 100 will not sufficientlycreate shear between the layers of the web, which is required toselectively break the hydrogen bonds.

FIG. 20 is an even further enlarged view of several inter-engaged teeth100 and grooves 108 with a web 10 of material therebetween. As shown, aportion of a web 10, which can be precursor web such as shown in FIG. 1,is received between the inter-engaged teeth 100 and grooves 108 of therespective rolls. The inter-engagement of the teeth 100 and grooves 108of the rolls causes laterally spaced portions 12 of web 10 to be pressedby teeth 100 into opposed grooves 108. In the course of passing betweenthe forming rolls, the web bends around the teeth 100, inducing shearforces in the web that result in the selective breakage and preservationof hydrogen bonds and disentanglement of the fibers. As shown in FIG.20, the teeth 100 do not penetrate through the thickness of theprecursor web 10. (However, in other embodiments such as when the rollsare rotated at different speeds, the teeth may penetrate through thethickness of the precursor web 10.) The teeth described here has asmaller tip radius TR than male elements in typical embossing processesto ensure the amount of compaction of the material 10 is minimized asthe material is being bent over the teeth 100. Also, unlike embossing,the clearance between the teeth, or the shortest distance D between thetips of the teeth 100 of the tooling described here, may be smaller thanthe thickness of the web 10 to induce additional shear forces in theweb. This results in a greater amount of de-densification of thematerial because hydrogen bonds are not only broken on the outersurfaces of the web but also may be broken inward of the outer surfacesof the web. In addition, the forces of teeth 100 pressing web 10 intoopposed grooves 108 impose within web 10 tensile stresses that act inthe cross-web direction. The tensile stresses can cause intermediate websections 12 that lie between and that span the spaces between the tipsof adjacent teeth 100 to stretch or extend in a cross-web direction,which can also result in the breakage of hydrogen bonds between thefibers and the disentanglement of fibers. Tensile stresses areundesirable because they do not selectively break hydrogen bonds, ratherthe hydrogen bonds can be broken throughout the entire thickness of theweb and in an uncontrolled manner. Therefore, unlike in priorapplications of SELFing technology, the depth of engagement E of therolls is kept low to minimize the tensile stresses put on the web 10. Ifthe tensile stresses become too large, the web will become very weak,fracture and be difficult to process. It will also not perform as wellin use because the continuity of the fibrous matrix is broken.

Because of the localized cross-web stretching of web 10 that has takenplace, with the consequent increase in web width, the web material thatexits from the forming rolls can have a lower basis weight than that ofthe entering web material, provided the exiting material remains in asubstantially flat, laterally extended state. The resulting modified webcan have a web width that can range from about 100% to about 150% of theinitial web width and a basis weight that is less than or equal to theweb's original basis weight.

For making an absorbent member 20 such as that shown in FIG. 2 from aprecursor web having a basis weight in the range of from about 200 to700 gsm, the teeth 100 may have a length TL ranging from about 0.5 mm(0.020 inch), or less, to about 10 mm (0.400 inch) and a spacing TD fromabout 0.5 mm (0.020 inch) to about 10 mm (0.400 inch), a tooth height THranging from about 0.5 mm (0.020 inch) to about 10 mm (0.400 inch), atooth tip radius TR ranging from about 0.05 mm (0.002 inch) to about 0.5mm (0.020 inch), and a pitch P between about 1 mm (0.040 inches) and 10mm (0.400 inches). The depth of engagement E can be from about −1 mm(−0.040 inch) to about 5 mm (0.200 inch) (up to a maximum approachingthe tooth height TH). Of course, E, P, TH, TD, TL, and TR can each bevaried independently of each other to achieve the desired properties inthe absorbent member. In one embodiment of roll useful for making anabsorbent member such as that shown in FIG. 2, teeth 100 have a uniformcircumferential length dimension TL of about 0.080 inch (2 mm) measuredgenerally from the leading edge LE to the trailing edge TE, a tooth tipradius TR at the tooth tip of about 0.005 inch (0.13 mm), are uniformlyspaced from one another circumferentially by a distance TD of about0.080 inch (2 mm), have a tooth height TH of 0.138 inch (3.5 mm), have atooth side wall angle of about 8.5 degrees (measured from the base ofthe tooth to near the tip of the tooth, before the formation of theradius), and a have a pitch of about 0.080 inch (2 mm). The clearancebetween the teeth of mating rolls linearly varies with the depth ofengagement. For this embodiment, the clearance of the teeth fornon-meshing rolls at −0.010 inch (0.25 mm) depth of engagement is 0.034inch (0.86 mm) and the clearance for meshing rolls at 0.015 inch (0.38mm) depth of engagement is 0.029 inch (0.74 mm).

The process used herein differs from Procter & Gamble's SELF process ina number of respects. One distinction is that the web materialsdescribed herein will typically not be formed into structures providedwith rib-like elements and elastic-like properties. Rather, the SELFprocess is used in the present context to mechanically deform theprecursor web material 10 and induce shear forces in localized areas 12between the teeth 100 of the forming structures in order to flex the web10 and selectively break hydrogen bonds to reduce the density andincrease the flexibility of the precursor web material. Anotherdistinction is that, in the case of some roll configurations usedherein, the thickness of the web may be substantially greater than theDOE in the present process.

Previously, it was believed that a DOE less than the thickness of theweb 10 would not be effective. However, in the processes describedherein, the DOE may be negative or less than the thickness of the web.(Although in the case of some roll configurations, such as pin rolls,the depth of engagement may be greater than the thickness of the webbecause such forming elements provide more clearance between adjacentelements, and a higher DOE is needed for the desired shear and bendingof the precursor web by such elements.) The first two examples in thetable below represent typical settings for prior SELFing applications,showing the ratio of thickness to DOE is typically much less than 1. Thethird and fourth examples in the table below represent examples ofsettings for the current processes, showing the ratio of thickness toDOE is typically equal or greater than 1. For negative DOE values, theratio of thickness to DOE is obtained by dividing the thickness by theabsolute value of the DOE.

Material Ratio of Thickness Thickness to Material (inches/mm) DOE(inches/mm) DOE PE film  0.001/0.025 0.040/1.0 0.025 Spunbond nonwoven0.020/0.51 0.090/2.3 0.22 Drylap 200 gsm 0.020/0.51  0.015/0.38 1.3Drylap 680 gsm 0.060/1.5   0.001/0.025 60

Numerous variations of the process described herein are possible. Theprocesses described herein can be configured and controlled to locallybend the precursor material 10 in opposite directions in the samelocation across the surface of the web when the web passes from one nipto another. The apparatus can also be configured and controlled tolocally bend the precursor material 10 in different locations across thesurface of the web when the web passes from one nip to another. It isdesirable for the rolls to be patterned and arranged such that theprecursor material is deformed in the greatest number of differentlocations on the surface before exiting the process, and so that this isaccomplished in the fewest number of hits and/or in the smallest processfootprint. The rolls can have staggered or standard patterns. The rollscan be aligned or mis-aligned relative to each other in the MD and/orCD. The rolls may all have the same SELF pattern thereon, or the patternon the rolls and/or DOE can vary between rolls (that is, for each passthrough a nip). The desired DOE for each pass depends on caliper of theprecursor material at each pass. An example of an apparatus thatmaximizes the de-densification of the material 10 in a small processfootprint is shown in FIG. 21. As shown in FIG. 21, the apparatusincludes rolls 100 with staggered patterns arranged in a hybridarrangement such that there are multiple three to four nested rollclusters 112 that are then off-set relative to each other in the CD.

The apparatus for de-densifying the precursor material can be providedat any suitable location, or stage, in the process of manufacturing anabsorbent article. In some embodiments, the method can serve as apre-processing step prior to feeding the precursor material into ahammer mill in order to reduce the energy required to defibrillate thematerial in the hammer mill. In other embodiments, the method andapparatus can be provided instead of a hammer mill at a location apartfrom an absorbent article manufacturing line, such as at the locationformerly occupied by the hammer mill. In still other embodiments,instead of being in a separate location from the absorbent articlemanufacturing line, the apparatus for de-densifying dry lap can belocated as a unit operation at or near the beginning (or at some otherconvenient location) of an absorbent article manufacturing line in orderto prepare a completed absorbent member that is ready for use in anabsorbent article being made on the line.

It may be desirable to make the width of the roll of precursor materialequal to the width or length of the absorbent core, or other structuredesired to be formed so that the roll of absorbent member material canbe conveniently cut into individual cores.

The process described above, thus, may use an apparatus that has maleelements on opposing surfaces in contrast to embossing apparatuses thatemploy male elements on one surface and female elements within which themale elements fit, on an opposing surface. In addition, in the presentprocess, the clearance between the elements may be less than thethickness of the web. This may be used to apply increased shear forceson the web (in contrast to apparatuses that require that the clearancebetween elements be greater than or equal to that of the web beingprocessed). The process described herein may be capable of not onlybreaking weak hydrogen bonds on the surface of the precursor material tosoften the surface of the same, it may also selectively break thestronger hydrogen bonds and those bonds towards the interior of thematerial and significantly de-densify and weaken the web. It can also beused to significantly increase the caliper (measured under load) of theprecursor web. The structure of precursor web can be preserved incertain zones for strength while hydrogen bonds can be broken in otherzones for acquisition.

B. Method for Making One-Side De-Densified Absorbent Members

In the methods for making one-side de-densified absorbent members, theprecursor web 10 is subjected to multiple passes through a nip formedbetween rolls having discrete forming elements thereon and opposingrolls that have a relatively smoother surface pattern.

FIG. 22 shows an embodiment of an apparatus for making a one sidede-densified absorbent member 20 such as that shown in FIG. 5. In thisembodiment, the apparatus provides a plurality of nips N between rollshaving forming elements thereon, and opposing rolls that have arelatively smoother surface pattern. FIG. 22 shows a nested rollapparatus in which the rolls 114 on a first side 10A of the precursorweb 10 have forming elements thereon, and the rolls 116 on the secondside 10B of the precursor web 10 have a relatively smoother surfacepattern. In the embodiment shown, each roll 116 having a relativelysmoother surface pattern forms a nip N with two rolls 114 having formingelements thereon.

In such an embodiment, the rolls 114 having forming elements thereon cancomprise any suitable type of roll having discrete forming elementsthereon including, but not limited to any of the configurations of SELFrolls and RKA rolls described above in conjunction with the method ofmaking the two-side de-densified absorbent members.

The rolls 116 with the relatively smooth surface can comprise anysuitable type of roll having a smoother surface than that of the rollhaving forming elements thereon. The rolls 116 with the relativelysmooth surface include, but are not limited to: flat anvil rolls, ringrolls (in which the ridges and grooves are either MD or CD oriented);or, another SELF roll of the same or different pattern than the rollhaving forming elements thereon. In cases in which the rolls 116 withthe relatively smooth surface comprise either a ring roll or a SELFroll, such a roll could have elements thereon with a smaller pitch thanthe roll having forming elements thereon or with a larger tip radius. Incases in which the rolls 116 with the relatively smooth surface comprisea SELF roll, such a roll could have elements thereon with longer teethand/or smaller MD spacing between the teeth to make them more like ringrolls.

In two non-limiting examples, the nip N could be formed by either a SELFroll and a flat anvil roll, or a SELF roll and a ring roll. Thecombination of a SELF roll and a flat anvil results in less overallde-densification, higher interior maximum density, and higher exteriordensity of the surface of the precursor web that is passed through thenip N against the anvil roll. The combination of a SELF roll and asmaller pitch ring roll will result in a shift in the location of themaximum interior density in the absorbent member 20, but the maximuminterior density will be lower and both exterior surfaces of theabsorbent member 20 will be more highly de-densified (in comparison tothe combination of a SELF roll and an anvil roll).

In this method, the forming elements on said first forming member, rolls114 having forming elements thereon penetrate into the first surface 10Aof said precursor web material 10 only part of the way into thethickness of the precursor web material, and the second surface 10B ofsaid precursor web material is in contact with the surface of the secondroll, rolls 116 with the relatively smooth surface.

C. Method for Making Re-Densified/Compacted Absorbent Members

The method of making a re-densified/compacted absorbent member involvesfirst de-densifying a precursor web material 10 using one of theapproaches described above for forming either the two-side or one-sidede-densified absorbent members. The de-densified absorbent material isthen compacted. The de-densified absorbent material can be compacted inany suitable manner. The de-densified absorbent material can becompacted over its entire surface, or in select areas/regions in the x-yplane.

FIG. 23 shows one non-limiting embodiment of an apparatus for making are-densified/compacted absorbent member 20 such as that shown in FIG. 7.As shown in FIG. 23, the apparatus may comprise a nested rollarrangement 120 similar to that shown in FIG. 15B or FIG. 22. After theprecursor web 10 passes through the nested roll arrangement 120, it isthen fed through an additional compacting station 122, which maycomprise a pair of rolls that form a nip therebetween. Options for theforming structures in this compacting station 122 include the followingcombinations: flat anvil on flat anvil (in order to compact all over);patterned roll on flat anvil (to compact select areas); or patternedroll on patterned roll (in order to compact select areas). In thedensifying/compacting process, the patterned roll (such as ring roll)should have regions that are relatively smoother than the surfaces ofthe forming members used in the de-densifying step.

D. Method for Making Three Dimensional Absorbent Members

The method of making a three dimensional absorbent member involvessubjecting the precursor web to a process for forming a threedimensional structure into the precursor web before and/or after it isde-densified such as described in sections IIA or B above. The method ofmaking a three dimensional absorbent member, thus, may involve firstde-densifying a precursor web material, such as by using one ofapparatuses described above for forming either the two-side and one-sidede-densified structures. The de-densified absorbent material is thensubjected to a further mechanical deformation step using forming membershaving forming elements thereon that have a greater MD and/or CD spacingtherebetween than the forming elements used in the prior steps and agreater depth of engagement. The de-densified absorbent material can besubjected to a further mechanical deformation step in any suitablemanner. Alternatively, the precursor web material could first besubjected to a mechanical deformation step using forming members havingforming elements thereon that have a greater MD and/or CD spacingtherebetween and a greater depth of engagement and then de-densifiedusing one of the approaches described above.

FIG. 24 shows one non-limiting embodiment of an apparatus for making athree-dimensional absorbent member such as those shown in FIG. 8. Asshown in FIG. 24, the apparatus may comprise a nested roll arrangement120 similar to that shown in FIG. 15B or FIG. 22. Before the precursorweb 10 passes through the nested roll arrangement 120, it is fed throughan initial three-dimensional forming station 124, which may comprise apair of rolls that form a nip therebetween. In alternative embodiments,the precursor web 10 can be passed through the nested roll arrangement120, and then fed through a three-dimensional forming station 124. Anapparatus for carrying out this later process would be similar to theapparatus shown in FIG. 23 where the compacting station 122 is replacedwith a three-dimensional forming station 124.

The three-dimensional forming station 124 can comprise any suitablecombination of forming members that are capable of imparting athree-dimensional texture to the precursor web 10. At least one of theforming members, which will be referred to as the three-dimensionalforming member, should have male elements thereon having a pitch that isgreater than the pitch of the elements used for de-densification.Several examples of three-dimensional forming rolls are described below.The direction of the ridges or teeth on the opposing roll should be thesame as that on the three-dimensional forming roll. The depth ofengagement of the elements on the three-dimensional forming roll withthe forming elements on the opposing roll is typically at least 0.04inch (1 mm). Any roll satisfying the above requirements can be used asthe opposing roll. The opposing roll can, for example, be either a ringroll or a SELF roll.

FIG. 25 shows one non-limiting example of a three dimensional formingroll 126 for the step of forming the precursor web 10 into a threedimensional absorbent member. As shown in FIG. 25, the forming roll 126comprises a larger pitch CD SELF roll in which the teeth 128 areoriented in the machine direction, and are staggered. In the embodimentshown in FIG. 25, the tips 130 of the teeth 128 are concave. FIG. 26shows another example of a forming member 132 for the step of formingthe precursor web 10 into a three dimensional absorbent member. As shownin FIG. 26, the forming member 132 comprises an MD SELF roll in whichthe teeth 134 are oriented in the CD and are staggered. The roll 132 hasspaced apart channels 136 formed therein that are oriented around thecircumference of the roll. Examples of suitable forming element (ortooth) dimensions and DOEs for the rolls shown in FIGS. 25 and 26 areprovided below. The forming elements on the opposing ring roll or SELFroll may have the same pitch as the rolls described below.

Large Pitch SELF MD SELF Pattern Staggered Staggered Pitch 200 185 Toothlength 0.118 in. (3 mm) 0.250 in. (6.4 mm) Tooth spacing 0.328 in. (8.3mm) 0.250 in. (6.4 mm) Tip radius 0.010 in. (0.25 mm) 0.010 in. (0.25mm) Tip shape Concave Flat DOE for 3D samples 0.105 in. (2.7 mm) 0.090in. (2.3 mm)

E. Method for Making Apertured Absorbent Members

The method of making an apertured absorbent member involves aperturing aprecursor web material before and/or after de-densifying the precursorweb material, such as by using one of approaches described above forforming the two-side and one-side de-densified structures. The apparatusfor making an apertured absorbent member may, thus, utilize a rollarrangement similar to that shown in FIG. 23 or 24, for example.However, the additional station or nip will comprise an aperturingforming member.

The precursor web 10 can be apertured in any suitable manner. Anyaperturing processes known in the art can be used including, but notlimited to: RKA rolls, or (high DOE) SELF rolls in which the DOE isgreater than thickness of web to create apertures. The precursor web 10can be apertured over its entire surface or in regions.

FIG. 27 shows one non-limiting example of an aperturing station 140 forthe step of forming the precursor web 10 into an apertured absorbentmember. As shown in FIG. 27, aperturing station 140 comprises a pair ofcounter-rotating, intermeshing rollers, wherein the top roll 142 is aring roll, and the bottom roll 144 is a Rotary Knife Aperturing (or“RKA”) roll. As shown in FIG. 27, the top ring roll 142 comprisescircumferentially-extending ridges 146 and grooves 148. The bottom roll144 comprises circumferentially-extending alternating rows of teeth 150and grooves 152. The teeth 150 are joined to the bottom roll at theirbases. The teeth 150 are tapered from their base to their tip, and thebase of the teeth have a cross-sectional length dimension greater than across-sectional width dimension. Typically, apertures are formed in theweb material 10 as the teeth on the RKA roll intermesh with grooves onthe ring roll 142. RKA rolls are described in greater detail in U.S.Patent Application Publication No. US 2006/0087053 A1.

F. Method for Making Absorbent Members Having X-Y Regions With DifferentDensities

1. Entire Absorbent Member Has Density Profile.

In some embodiments, the entire absorbent member may have a densityprofile, and the absorbent member may have different regions in the X-Yplane with different densities and/or different density profiles. Onemethod of making an absorbent member having X-Y regions with differentdensities and/or density profiles is similar to the method of making are-densified/compacted absorbent member. In order to make an absorbentmember having X-Y regions with different densities, after de-densifyingthe absorbent material, the de-densified absorbent material is compactedonly in select areas/regions in the x-y plane.

FIG. 28 shows one non-limiting example of a forming member 160 for thestep of forming the precursor web 10 into an absorbent member with adensity profile and different regions in the X-Y plane with differentdensities and/or different density profiles. As shown in FIG. 28, theforming member 160 comprises a roll having a region 162 thereon forcompacting the de-densified absorbent material only in selectareas/regions in the x-y plane. The region 162 on the roll 160 can beprovided with any of the properties described above in conjunction withthe preparation of a re-densified/compacted absorbent member.

Various alternative methods can be used to produce an absorbent memberhaving X-Y regions with different densities and/or density profiles.Other alternative processes for producing such a structure includevarying the depth of engagement (DOE), tooth geometry (TL, TD, TR),pitch, or number of hits for a specific region such that the region ismore or less de-densified than the other regions of the absorbentmember. Still other alternative methods for producing an absorbentmember having X-Y regions with different densities and/or densityprofiles can involve de-densifying the precursor material using acombination of approaches, such as the de-densification step describedin sections IA or B above, plus the “regional de-densification” processdescribed in F2 below.

2. Absorbent Members with “Regional De-Densification.

The method of making an absorbent member with regional de-densificationmay be similar to the methods of de-densifying the precursor web such asdescribed in sections IIA or B above. In order to make an absorbentmember with regional de-densification, the precursor web is de-densifiedonly in select areas/regions in the x-y plane. This can be done byproviding selected portions of the forming structures which are free offorming elements such that they will leave portion(s) of the precursorweb material in their original state. The portions of the formingstructure which are free of forming elements can be substantiallysmooth. These portions of the forming structures can be arranged so thatthey align with one or more portions of the precursor web.

FIG. 29 shows one non-limiting example of a forming structure for thestep of forming the precursor web into an absorbent member with regionalde-densification. As shown in FIG. 29, the forming structure 170comprises two spaced apart pairs 172 and 174 of counter-rotating rollsthat rotate on the same axes. The rolls may comprise any of the types ofrolls described herein for de-densifying the precursor web. When theprecursor web is fed into the nip N between the pairs of rolls 172 and174, the portions of the precursor web (such as along the longitudinalside regions of the web) contacted by the rolls 172 and 174 will bede-densified, while the central region of the web the is in the gap 176between the rolls is not. In other embodiments, the arrangement of theforming structure shown in FIG. 29 can be varied to de-densify anysuitable region(s) of the precursor web.

G. Alternative Embodiments and Combinations

The methods described herein may be used for a variety of purposes. Suchpurposes can range from serving as a pre-processing step prior tofeeding the precursor material into a hammer mill in order to reduce theenergy required to defibrillate the material in the hammer mill, toserving as a unit operation in an absorbent article manufacturing linein order to prepare a completed absorbent member that is ready for usein an absorbent article being made on the line.

Numerous alternative embodiments and combinations of the foregoingmethods are possible. For instance, a precursor web can be fed throughthe apparatuses described herein any number of times, and the web can bethereafter fed through another one of the apparatuses any number oftimes. In addition, as shown in FIGS. 12 and 13, more than one absorbentmember can be combined to form still other absorbent structures, andthese absorbent structures can be fed together through any of theapparatuses described herein. In one non-limiting example, a precursorweb can be fed through 20 passes of regional de-densification followedby five passes of all-over de-densification. The web can then becombined with a second de-densified layer and apertures can be formed ina region through both layers.

III. Examples

TABLE 1 Drylap Precursor Materials 680 gsm Drylap 300 gsm Drylap AverageDensity (g/cc) 0.51 0.44 Location of Maximum (%) 77 91 Mean MaximumDensity (g/cc) 0.54 0.47 Location of Minimum (%) 95 7 Mean MinimumDensity (g/cc) 0.49 0.42 Ratio of Density Means 1.1 1.1 Maximum/MinimumRatio of Density Means 1.1 1.1 Maximum/Outer 5-15% Ratio of DensityMeans 1.1 1.0 Maximum/Outer 85-95% Flexure-Resistance (N) 81.0 28.1 CDPeak Tensile (N) 320.6 111.6 MD Peak Tensile (N) 395.1 175.7

Table 2 below shows the caliper increase of various drylap samples after30 passes between nips formed between an 80 pitch staggered SELF rolland another 80 pitch staggered SELF of the type shown in FIGS. 16 and 17at 0.000 inch (0 mm) depth of engagement and 50 feet per minute (15meters/minute) line speed. When a number, such as “80” is given todescribe the pitch, this refers to the number in thousands of an inch.The 80 pitch staggered SELF rolls have a diameter of 5.7 inch (14.5 cm),a uniform circumferential length dimension TL of about 0.080 inch (2 mm)measured generally from the leading edge LE to the trailing edge TE, atooth tip radius TR at the tooth tip of about 0.005 inch (0.13 mm), areuniformly spaced from one another circumferentially by a distance TD ofabout 0.080 inch (2 mm), have a tooth height TH of about 0.138 inch (3.5mm), have a tooth side wall angle of about 8.5 degrees, and a have apitch of about 0.080 inch (2 mm). The SELF rolls are aligned in the CDsuch that the clearances on either side of the teeth are about equal.The clearance between the teeth of mating rolls linearly varies with thedepth of engagement, ranging from a clearance 0.034 inch (0.86 mm) at−0.010 inch (0.25 mm) depth of engagement to a clearance of 0.029 inch(0.74 mm) at 0.015 inch (0.38 mm) depth of engagement. The rolls have astaggered tooth pattern and have square (vs. rounded) shape on theleading and trailing edges of the teeth, like that shown in FIG. 18.

TABLE 2 Increase in Caliper of Drylap Samples of Various Burst StrengthsGP 4825 BoWater GP 4821 Tartas Bio Semi- Coos GP 4800 Treated Fluff TDRtreated Absorb SE Untreated Precursor 416 599 630 1143 1549 MaterialBurst Strength (kPa) Ave Base 1.50 1.80 1.50 1.72 1.40 Caliper (mm; n =3) Ave Caliper 4.50 4.14 3.70 2.86 2.81 Post SELFing (mm; n = 9) Caliper3.00 2.34 2.20 1.14 1.41 Increase (mm)

Table 3 below shows the properties of various drylap samples after 30passes between nips formed between an 80 pitch staggered SELF roll andanother 80 pitch staggered SELF roll of the type shown in FIGS. 16 and17 at the specified depths of engagement (DOE) and a 50 feet per minuteline speed. The same 80 pitch staggered SELF rolls used to produce theExamples in Table 2 (described above) are used.

TABLE 3 Two Side De-Densified Absorbent Members Ex. 1 Ex. 2 Ex. 3 Ex. 4Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Target Material Basis Weight (gsm) 300 300500 400 400 680 680 300 300 # Passes 30 15 30 30 8 100 50 100 50 DOE(inches/mm) 0.010/0.25 0.010 0.005/0.127 0.007/0.18 0.007 −0.005 0.0050.005 0.015/0.38 Average Density (g/cc) 0.13 0.22 0.15 0.17 0.27 0.220.14 0.14 0.066 Location of Maximum (%) 49 44 54 58 63 52 58 48 47 MeanMaximum Density (g/cc) 0.22 0.31 0.25 0.30 0.38 0.38 0.24 0.21 0.010Location of Minimum (%) 5 95 5 5 5 14 20 5 6 Mean Minimum Density (g/cc)0.055 0.077 0.075 0.054 0.091 0.079 0.060 0.064 0.040 Ratio of DensityMeans 4.0 4.0 3.3 5.5 4.2 4.8 4.0 3.3 2.5 Maximum/Minimum Ratio ofDensity Means 4.0 1.6 3.3 5.5 4.2 4.9 3.7 3.3 2.5 Maximum/Outer 5-15%Ratio of Density Means 2.8 4.0 2.5 2.2 1.9 4.1 2.0 2.0 1.8 Maximum/Outer85-95% Flexure-Resistance (N) 1.2 1.9 4.8 3.5 13.6 7.9 2.4 1.7 0.3 MDPeak Tensile (N) 6.6 13.9 20.0 11.9 44.6 19.2 2.9 3.8 0.4

Table 4 below shows the properties of various drylap samples after thespecified number of passes between nips formed by rolls having thespecified configurations and at the specified depths of engagement (DOE)and a 50 feet per minute line speed. All of the rolls used to producethe materials have similar diameters of about 5.7 inch. The same 80pitch staggered SELF rolls used to produce the Examples in Table 2(described above) are used. The anvil roll has a smooth surface. The 40pitch ring roll has continuous ridges and grooves similar to the toproll (roll 142) shown in FIG. 27. The 40 pitch ring roll has a toothheight TH of about 0.080 inch and a tooth tip radius TR at the tooth tipof about 0.004 inch. The 80 pitch staggered SELF roll is aligned withthe 40 pitch ring roll such that there are two ring roll teethin-between each row of SELF teeth. The 80 pitch staggered SELF roll and40 pitch ring roll are aligned in the CD such that the clearances oneither side of the SELF teeth on the 80 pitch roll are about equal.

TABLE 4 One Side De-Densified Absorbent Members Example 10 Example 11Example 12 Example 13 Target Precursor Material 300 300 500 400 BasisWeight (gsm) Tooling Configuration 80 pitch 80 pitch 80 pitch 80 pitchStaggered SELF Staggered SELF Staggered SELF Staggered SELF againstSmooth against 40 pitch against 40 pitch against 40 pitch Anvil RingRoll Ring Roll Ring Roll # Passes 30 30 30 28 DOE (inches/mm)−0.003/−0.076 0.003/0.076 −0.010/−0.25 0.000 Average Density (g/cc) 0.420.15 0.46 0.26 Location of Maximum (%) 85 80 64 75 Mean Maximum Density(g/cc) 0.58 0.22 0.61 0.49 Location of Minimum (%) 5 5 5 5 Mean MinimumDensity (g/cc) 0.16 0.077 0.15 0.078 Ratio of Density Means 3.5 2.9 4.06.3 Maximum/Minimum Ratio of Density Means 3.5 2.9 4.0 6.3 Maximum/Outer5-15% Ratio of Density Means 1.0 1.5 1.2 1.7 Maximum/Outer 85-95%Flexure-Resistance (N) 5.3 1.2 18.9 5.9 MD Peak Tensile (N) 70.5 7.8122.0 28.0

Table 5 shows the difference in caliper and flexibility of a compactedtwo-side de-densified structure relative to an uncompacted two-sidede-densified structure. The compacted structure is thinner than theuncompacted structure, while maintaining similar flexibility. Example 14is produced by passing samples of 500 gsm drylap through a nip formedbetween an 80 pitch staggered SELF roll and another 80 pitch staggeredSELF of the type shown in FIGS. 16 and 17, 30 times, at 0.005 inch depthof engagement and a 50 feet per minute line speed. The same 80 pitchstaggered SELF rolls used to produce the Examples in Table 2 (describedabove) are used. Example 15 is de-densified in the same manner asExample 14, then compacted all over using a flat metal plate and a diepress.

TABLE 5 Compacted Absorbent Structures Average Average Target BasisMechanical Caliper Flexibility Weight (gsm) Treatment (mm) (N) Example14 500 30 pass 80 pitch 3.25 4.8 SELF on SELF at 0.005 inch (0.127 mm)DOE (no compaction) Example 15 500 30 pass 80 pitch 2.20 5.5 SELF onSELF at 0.005 inch DOE, then compacted

Table 6 shows an example in which a de-densified and compacted absorbentmember is thinner and more flexible than an absorbent member withprocessed with fewer passes. Example 16 is produced using the sametooling and settings as Example 14 above, but with only 17 passesthrough the nip. Example 17 is produced in the exact same manner asExample 15 above.

TABLE 6 Compaction versus Fewer Passes Precursor Material AverageAverage Target Basis Mechanical Caliper Flexibility Option Weight (gsm)Treatment (mm) (N) Example 16 500 17 pass 80 pitch 2.47 11.5 SELF onSELF at 0.005 inch DOE Example 17 500 30 pass 80 pitch 2.20 5.5 SELF onSELF at 0.005 inch DOE, then compactedIV. Test Methods

A. MicroCT Analysis of Absorbent Members for Density Determination

Micro-computed tomography (mCT) is used to quantitatively measure thedensity profile throughout the thickness of the absorbent membernon-invasively.

Scanning Protocol

A disposable absorbent article is removed from its packaging and laidflat, taking care to not disturb the absorbent member material. Specimendiscs 13.3 mm in diameter are cut from the center of the area to betested in the disposable absorbent article through its entire thicknessusing curved tip scissors. The specimen is preferably chosen in an areathat is free of embossments and apertures. The portion of the specimento be analyzed should only include the unitary absorbent member asdefined by the specification. The portion of the specimen to be analyzedcan be physically removed from the specimen prior to scanning if it canbe done in a way that does not disrupt the thickness or density of theportion of the specimen to be analyzed. Otherwise, the entire specimenis scanned and any additional material that is not part of the portionof the specimen to be analyzed should be digitally removed from theslices through cropping in step 2 below.

The specimen or portion of the specimen, herein after referred to assample, is imaged using a micro-computed tomography system (μCT 40,ID#4286, Scanco Medical AG) or equivalent instrument. A custom shortsample tube of length 30 mm and internal diameter 13.3 mm is used toposition the sample for scanning. A 2 mm thick spacer of suitablematerial with low x-ray attenuation (e.g. polystyrene foam) is used toprop the sample off of the bottom of sample tube to avoid anyattenuation interference from the plastic tube bottom. The sample ismounted horizontally with the top side of sample exposed to air with nocontact from other materials. Image acquisition parameters of the 3-Disotropic scan are high resolution (1000 projections) with the x-raytube set for a current of 180 μA and a peak energy of 35 kVp, with a 300millisecond integration time and frame averaging set at 10. Horizontalslices are acquired with a slice increment of 8 μm throughout thethickness of the sample. Each slice consisting of 2000 projections (1000projections/180 degrees) is used to reconstruct the CT image in a2048×2048 pixel matrix, with a pixel resolution of 8 μm. To eliminateany edge effects, only the central 7.2 mm×7.2 mm square area of eachslice is used for subsequent analysis.

Image Analysis

If the portion of the unitary absorbent member is physically removedfrom the specimen prior to insertion into the sample tube, then thecentral 7.2×7.2 mm square portion of the unitary absorbent member in thesample tube is subjected to image analysis as described below. If theentire specimen is inserted in to the sample tube, then only the central7.2×7.2 mm square portion of the unitary absorbent portion of thespecimen is subjected to the image analysis described below. In eithercase, the central 7.2×7.2 mm square portion will be referred to hereinas the portion of interest or POI.

The objective of the image analysis is to quantitatively measure thedensity distribution through the thickness of the POI and verify theuniformity of the POI using the following outputs:

-   -   Density distribution through the thickness of the POI (used to        quantify the density profile of the POI)    -   Average thickness for the entire POI and the 4 quadrants of the        POI (used in the acceptance criterion to verify sample        uniformity described below)

Acceptance Criteria: In order for a POI to be acceptable, it must have auniform thickness (i.e. the average thickness of each quadrant withinthe POI must be within 50% of the average thickness of the entire POI),as defined in step 12 below.

Image Analysis Procedure: After collection of 3-D MicroCT data in an ISQfile (the proprietary format for Scanco Medical microCT scanner), thedata are transferred to a Mac Pro workstation running RedHat 4 Linux, orequivalent computer system. Data analysis is performed using Matlab7.6.0.324 and Avizo 6.1 or equivalent software. The following steps areapplied to the 3-D data set:

-   -   1. The ISQ file is converted from 16 bit to 8 bit stack of TIFF        images using a scaling factor of 0.05 and an offset of 0. Each        image within the stack is cropped such that only the central 7.2        mm×7.2 mm square portion of the image remains.    -   2. Each stack of TIFF images from Step 1 is then examined using        AVIZO (VSG, Burlington, Mass.), a high end 3-D visualization        software application. Any noise or artifacts not desired in the        measured data set are removed using the VolumeEdit feature in        AVIZO.        -   Note: The editing step ensures that the data associated with            the POI will be accurate and extraneous data are removed.            This editing step must be done carefully or it can lead to            incorrect identification of the POI. Any additional material            used to secure the sample or not part of the POI should be            digitally removed from the slices through cropping out those            extraneous regions so they are not included in the analysis.    -   3. The cleaned data are then saved in AVIZO as a 3-D avw file.    -   4. The 3-D sample created in Step 3 is divided into four        quadrants. Each quadrant has the same Z dimension as the        original sample, but the X/Y dimensions are divided by 2. For        example a sample that was originally of dimensions 1000×1000×500        (X by Y by Z) pixels would be broken into four quadrants each        with dimensions of 500×500×500 pixels. Each quadrant, as well        the original data set is analyzed in an identical manner as        described in the steps below.    -   5. A threshold is chosen to separate the fibers from the        background. This is chosen using an automated method in Matlab        (Otso's method). The same threshold should then be used for all        subsequent scans of absorbent members of like material. Note:        Correct thresholding is an important variable to determine a        correct POI. A visual inspection should be performed as a check        to determine that this threshold seems optimal for the fiber        type.    -   6. Depth maps of top and bottom surfaces are then created. A        depth map is a 2-D image where the grey level value represents        the distance from the top of the POI to the surface of the        layer.    -   7. These depth images are then median filtered using 5        iterations of an 11×11 median filter to remove spurious fibers.        These depth images are then converted back to coordinates in 3-D        space and serve as the top and bottom surfaces of the absorbent        member.        -   Note: Increased/Decreased median filtering will allow more            of the fibers to be included and will make the POI larger.            The amount of median filtering should not change within a            study and the resulting POI should be inspected visually            after analysis.    -   8. The thickness of the POI is calculated by subtracting the top        and bottom depth maps. An average of the non-zero values of this        subtraction provides the average thickness of the POI.    -   9. Starting from the top surface the density is normalized to        0-100%, where the percentages represent the Z-direction location        throughout the thickness of the web (0%—top surface, 100%—bottom        surface). At each percentage point in-between the grey level        value is recorded. This is repeated for all points in the POI.    -   10. The absorbent member data are converted to a 3-D Volume that        has the same X/Y dimensions as the original data, but the Z        dimension is now 100, reflecting the percentage through the        sample.    -   11. A histogram is created of the mean of all the grey levels at        1%, 2%, 3%, . . . 100%. A .csv file is created and sent to        Excel.    -   12. In order to determine if the thickness of the POI is        uniform, the average thickness of each the 4 quadrants, which is        determined in step 8, should be verified to be within 50% of the        average thickness determined for the overall POI. If one or more        quadrants are ≧50% different, then a new specimen is selected        and analyzed.        Calibration of Density

In order to calibrate the relationship between the output grey leveldata from Step 11 to relevant density values, a small calibration studyis performed using standard foams with known densities. The density ofthe calibration samples is determined by die cutting a cube andmeasuring the length (L), width (W) and height (H) of the sample usingthe caliper method defined below, measuring the weight of the sample tothe nearest 0.01 g using a calibrated balance, then dividing the weightof the sample by the volume (L×W×H). The known density values of thecalibration samples are then correlated with the average grey levelvalues after measurement of the calibration samples by MicroCT using thesame scanning parameters as those used in this study.

Six calibration samples of homogeneous, commercially available,non-metallic foams, each having a different density and made of apolymeric material, are measured by the same protocol as describedabove. The calibration samples and the test specimens consistessentially of elements selected from carbon, hydrogen, oxygen andnitrogen atoms, and combinations thereof. The foam samples are chosen sothat the average density of the POI analyzed above lies between that ofthe least dense and most dense foam calibration samples. For each foamsample, the average grey value is determined from the center of the foamsample. i.e. 45% to 55%. This value is then plotted against the knowndensity of each foam sample. This produces a set of points to which aleast-squares regression is fitted (either linear or nonlinear).However, the correlation coefficient r² should be at least >0.90 for thelinear regression. For r² values less than 0.90, the calibration shouldbe re-done with different foam samples if necessary. The equationdescribing the regression is then used to convert the grey level valuesof the MicroCT data to density values measured in g/cc.

Calculations

-   -   1. The mean grey levels created in step 11 are converted to        density values for each z-direction location (i.e. 5%, 6%, 7%,        95%) using the calibration curve generated from the regression        described above.    -   2. To calculate the average density, the density values from        5-95% are averaged.    -   3. To calculate the mean outer 5-15% density, the density values        from 5-15% are averaged.    -   4. To calculate the mean outer 85-95% density, the density        values from 85-95% are averaged.    -   5. To calculate the mean maximum density, the maximum density        from 5-95% is located and the average density is calculated        using the data points ranging from (maximum −5%) to (maximum        +5%). For example, if the maximum is located at 45%, the mean        peak density is calculated using the density values from 40-50%.        If the maximum density falls at a location that is ≦10% through        the thickness of the sample, then the mean outer 5-15% density        calculation is used. If the maximum density falls at a location        that is ≧90% through the thickness of the sample, then the mean        outer 85-95% density calculation is used.    -   6. To calculate the mean minimum density, the minimum density        from 5-95% is located and the average density is calculated        using the data points ranging from (minimum −5%) to (minimum        +5%). For example, if the minimum was located at 15%, the mean        peak density is calculated using the density values from 10-20%.        If the minimum density falls at a location that is ≦10% through        the thickness of the sample, then the mean outer 5-15% density        calculation is used. If the minimum density falls at a location        that is ≧90% through the thickness of the sample, then the mean        outer 85-95% density calculation is used.    -   7. To calculate the ratio of the mean maximum density to the        mean minimum density, the mean maximum density is divided by the        mean minimum density.    -   8. To calculate the ratio of the mean maximum density to the        mean outer 5-15% density, the mean maximum density is divided by        the mean outer 5-15% density.    -   9. To calculate the ratio of the mean maximum density to the        mean outer 85-95% density, the mean maximum density is divided        by the mean outer 85-95% density.

B. Flexibility Method

The flexibility of the absorbent member is quantified by measuring thepeak bending stiffness, or flexure-resistance, following the CIRCULARBEND PROCEDURE. The lower the value, the lower the flexure-resistance,and the higher the flexibility of the sample.

Apparatus

The apparatus necessary for the CIRCULAR BEND PROCEDURE is a modifiedCircular Bend Stiffness Tester, having the following parts:

-   -   1. A smooth-polished steel plate platform which is        102.0×102.0×6.35 millimeters having an 18.75 millimeter diameter        orifice centered within the plate. The lap edge of the orifice        should be at a 45 degree angle to a depth of 4.75 millimeters.    -   2. A plunger having an overall length of 72.2 millimeters, a        diameter of 6.25 millimeters, a ball nose having a radius of        2.97 millimeters and a needle-point extending 0.88 millimeter        therefrom having a 0.33 millimeter base diameter and a point        having a radius of less than 0.5 millimeter, the plunger being        mounted concentric with the orifice and having equal clearance        on all sides. The bottom of the plunger should be set well above        the top of the orifice plate. From this position, the downward        stroke of the ball nose is to the exact bottom of the plate        orifice.    -   3. A 100 N load cell (Model # SMT1-100N) or equivalent.    -   4. An actuator, and more specifically an MTS Synergie 400 (Model        #SYN400), or equivalent.        Number and Preparation of Specimens

In order to perform the procedure for this test, as explained below, aminimum of four representative samples are necessary. Using a diecutter, a square 37.5×37.5 millimeter test specimen is cut from eachsample. The specimen is cut from the center of the sample (e.g. centeredon the intersection of the longitudinal and transverse centerlines). Theportion of the specimen to be tested should only include the unitaryabsorbent member as defined by the specification. Therefore, the othermaterials that are not part of the absorbent member must be carefullyremoved, and test specimens should not be folded or bent by the testperson to avoid affecting flexural-resistance properties.

Procedure

The procedure for the CIRCULAR BEND PROCEDURE is as follows. The testplate is leveled. The plunger speed is set at 50.0 centimeters perminute per full stroke length. A specimen is centered on the orificeplatform below the plunger such that the body surface of the specimen isfacing the plunger and the garment surface of the specimen is facing theplatform. The indicator zero is checked and adjusted, if necessary. Theplunger is actuated. Touching the specimen during the testing should beavoided. The maximum force reading to the nearest 0.1 N is recorded. Theabove steps are repeated until all four of the specimens have beentested.

Calculations

The peak bending stiffness, or flexure-resistance, for each specimen isthe maximum force reading for that specimen. Each specimen is measuredindividually and the average of the samples is reported to the nearest0.1 N.

C. Caliper Method

Apparatus

The caliper of the material is quantified using a Thwing-Albert ProGageThickness Tester or equivalent with a 56.4 millimeter diameter circularfoot.

Number and Preparation of Specimens

A minimum of 3 representative samples are necessary to complete thetesting. One specimen is cut from each of the 3 samples for a total of 3test specimens. The specimen is cut from the center of the sample (e.g.centered on the intersection of the longitudinal and transversecenterlines). The portion of the specimen to be tested should onlyinclude the unitary absorbent member as defined by the specification.Therefore, the other materials that are not part of the absorbent membermust be carefully removed such that the caliper of the material is notimpacted. The specimens to be measured must be ≧65 millimeters indiameter to ensure the entire surface area of the foot comes in contactwith the sample being measured. The highlighted text obviously does notapply to the calibration foam materials for which this method is used.

Procedure

The test apparatus is always zeroed before any measurements are taken.The foot starts 0.5 inches above the surface on which the test specimenis placed and descends at a rate of 0.125 inches per second. When thefoot reaches the target pressure of 0.51 kilopascals, it remains incontact with the specimen for 9 seconds while maintaining that pressure.The reading is taken at the end of the 9 second period.

Calculations

Each of the samples is individually measured and the average of thesamples is reported to the nearest 0.01 millimeters.

D. Tensile Method

The MD and CD peak tensile are measured using a method based on StandardTest WSP 110.4 (05)—Option B, Standard Test Method for Breaking Forceand Elongation of Nonwoven Materials (Strip Method), but with a shortergauge length to enable measurements on finished products.

Apparatus

The apparatus necessary for the TENSILE METHOD consists of the followingparts: 1) An MTS Synergie 400 (Model #SYN400) or equivalent with aconstant-rate-of-extension of 100 mm/min; 2) A 100 N load cell (Model#SYN100) or equivalent, or a 500 N load cell (Model #SYN 500) orequivalent for stiffer materials such as undeformed drylap.

Number and Preparation of Specimens

A minimum of eight representative samples are necessary, four for the MDtensile test and four for the CD tensile test. The specimen is cut fromthe center of the sample (e.g. centered on the intersection of thelongitudinal and transverse centerlines). The portion of the specimen tobe tested should only include the unitary absorbent member as defined bythe specification. Therefore, the other materials that are not part ofthe absorbent member must be carefully removed such that the tensilestrength of the material is not impacted. To prepare the samples for theMD tensile test, a specimen is die cut from each sample with a CD widthof 50 mm and a MD length of 70 mm. For a sample that is being taken froma product, such as a feminine pad, the MD is assumed to represent thelong direction of the pad and the CD is the direction orthogonal to theMD. To prepare the samples for the CD tensile test, a specimen is diecut from each sample with a MD length of 50 mm and a CD width of 50 mm

Procedure

Standard Test WSP 110.4 (05)—Option B is followed with the followinggauge length changes:

1. MD peak tensile: 50 mm gauge length

2. CD peak tensile: 30 mm gauge length

Calculations

The peak tensile is the maximum force reading for that specimen. Eachspecimen is measured individually and the average peak MD tensile andaverage peak CD tensile of the samples is reported to the nearest 0.1 N.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 grams” is intended tomean “about 40 grams”.

It should be understood that every maximum numerical limitation giventhroughout this specification includes every lower numerical limitation,as if such lower numerical limitations were expressly written herein.Every minimum numerical limitation given throughout this specificationwill include every higher numerical limitation, as if such highernumerical limitations were expressly written herein. Every numericalrange given throughout this specification will include every narrowernumerical range that falls within such broader numerical range, as ifsuch narrower numerical ranges were all expressly written herein.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this written document conflicts with any meaningor definition of the term in a document incorporated by reference, themeaning or definition assigned to the term in this written documentshall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An absorbent member comprising a unitary wetlaidabsorbent fibrous layer comprising at least about 95 percent cellulosefibers per weight of the absorbent fibrous layer, said absorbent fibrouslayer having a first surface, a second surface, a length extending in anX-direction, a width extending in a Y-direction, and a Z-directionthickness, wherein the thickness of the absorbent fibrous layer can bedivided into a range of distances measured through its thickness from 0%at its first surface to 100% of the distance through its thickness atits second surface, and the length and width of the absorbent fibrouslayer define an area, wherein at least a 7.2×7 2 mm square area of theabsorbent fibrous layer has an average density, and a density profilethrough its thickness comprising a location having a maximum density, alocation having a minimum density, a mean maximum density, and a meanminimum density, said absorbent fibrous layer comprising a relativelyhigher density zone disposed in the Z-direction adjacent to a relativelylower density outer zone of the layer, wherein: a) the maximum densityof the layer is located outside of the central 20% zone of the thicknessof the layer; and b) the mean maximum density measurement through thethickness of the layer is at least about 1.2 times the mean density ofthe layer measured at one of the outer zones of the layer that are: (1)between 5% to 15%; and (2) between 85% and 95% of the thickness of thelayer.
 2. The absorbent member of claim 1 wherein the maximum density ofthe layer is located outside of the central 40% zone of the layer. 3.The absorbent member of claim 1 wherein the maximum density of the layeris located outside of the central 60% zone of the layer.
 4. Theabsorbent member of claim 1 wherein the mean maximum density measurementthrough the thickness of the layer is at least about 2.5 times the meandensity of the layer measured at one of the outer zones of the layer. 5.An absorbent article comprising a liquid pervious body-facing side, aliquid impervious side, and an absorbent member according to claim 1between the body-facing side and the impervious side, wherein therelatively lower density outer zone of the layer faces the body-facingside of the absorbent article and the relatively higher density zonefaces the liquid impervious side of the absorbent article.
 6. Theabsorbent member of claim 1 wherein the mean maximum density of theabsorbent member is greater than 0.25 g/cc.
 7. The absorbent member ofclaim 1 wherein the absorbent fibrous layer is substantially free ofabsorbent gelling material.
 8. The absorbent member of claim 1 whereinthe absorbent fibrous layer is substantially free of binders.
 9. Theabsorbent member of claim 1 wherein the absorbent fibrous layercomprises a precursor material selected from the group consisting of:drylap, liner board, paper board, post-consumer recycled material,filter paper, and combinations thereof.
 10. The absorbent member ofclaim 9 which comprises chemical debonders.
 11. The absorbent member ofclaim 1 wherein said cellulose fibers have surfaces and there areinterfiber hydrogen bonds between cellulose fibers in at least a portionof said layer that are substantially interrupted by void spaces betweensaid fibers surfaces.
 12. The absorbent member of claim 1 wherein thelocation having the minimum density and adjacent portions of theabsorbent fibrous layer through the thickness of the layer comprise azone that has a thickness that is at least about 10% of the thickness ofthe absorbent fibrous layer.
 13. The absorbent member of claim 1 whereinat least one of said first surface and second surface comprisesprotrusions, and at least one of said protrusions has a density profilewherein the mean maximum density in said at least one protrusion isbetween about 1.2 and about 6.5 times the mean minimum density measuredat the portion of the protrusion having a minimum density.
 14. Theabsorbent member of claim 1 wherein there is at least one apertureextending between said first and second surfaces of said absorbentmember.
 15. The absorbent member of claim 1 comprising at least tworegions that are 7.2×7 2 mm square extending in the X and Y directions,said at least two regions comprising: a) a first region having a densityprofile through its thickness comprising a portion of the area of theabsorbent fibrous layer, said first region having a having a firstregion mean maximum density, a first region mean minimum density, and afirst region average density, wherein the maximum density of the layeris located outside of the central 20% zone of the thickness of layer andthe first region mean maximum density measurement is at least about 1.2times the first region mean minimum density; and b) a second regionhaving a density profile through its thickness comprising a portion ofthe area of the absorbent fibrous layer, said second region having asecond region mean maximum density, a second region mean minimumdensity, and a second region average density, wherein the maximumdensity of the layer is located outside of the central 20% zone of thethickness of layer and the second region mean maximum density is atleast about 1.2 times the second region mean minimum density, andwherein the second region average density is at least about 0.05 g/ccgreater than the first region average density.
 16. A disposableabsorbent article comprising the absorbent member of claim 1, whereinsaid absorbent member is a component of said absorbent article selectedfrom the group consisting of: a liquid pervious topsheet; an acquisitionlayer; and an absorbent core.
 17. The absorbent member of claim 1wherein substantially about 100 weight percent of the fibers in saidabsorbent fibrous layer comprise cellulose fibers.
 18. The absorbentmember of claim 1 wherein the percentage of cellulose fibers in theabsorbent fibrous layer is substantially the same through the thicknessof the absorbent fibrous layer.